In the late 1980’s, extreme environmental contamination and pollution of soil and groundwater occurred at the manufacturing facility of Wysong & Miles Company (Wysong) in Greensboro, North Carolina. Wysong sought an environmental consultant to help it deal with the pollution and contamination. Wysong hired Delta Environmental Consultants of North Carolina, Inc. (Delta), a Charlotte-based subsidiary of a national environmental consulting and engineering firm, to assist Wysong in formulating and implementing a cleanup plan. In March or April 1988, Delta and Wysong entered a service contract for environmental services (first contract). On 24 February 1994, Delta and Wysong entered a second contract, which remained effective until Wysong terminated the Contract in April 1995. Over the course of their seven-year relationship, Delta performed tasks and billed Wysong on a time, fees, and materials basis. From October 1994 to April 1995, Wysong failed to pay Delta for the invoices it submitted each month. Despite being delinquent in payment, Wysong continued to ask Delta to perform work and in January 1995, assured Delta that it would bring its account current. In April 1995, Delta brought suit to collect $29,370.58. On 18 January 1996, Wysong amended its answer and counterclaimed against Delta. Wysong counterclaimed alleging unjust enrichment because Delta had received payment for work that had not actually been performed. Wysong’s counterclaim also alleged negligence in that Delta failed to perform its remedial work to the level of skill ordinarily exercised by members of its profession. Wysong’s motion to amend its answer and counterclaim to include allegations of unfair or deceptive acts or practices in commerce in violation of N.C. Gen. Stat. § 75-1.1 was denied.
*164 The matter was heard before a duly impaneled jury on 11 February 1997. The jury returned the following verdicts:
PLAINTIFF. DELTA. CLAIM:
1. Does the Defendant, Wysong, owe the Plaintiff, Delta money on account? YES
2. What amount if any does the Defendant, Wysong, owe the Plaintiff, Delta, on account? NONE
DEFENDANT. WYSONG. COUNTERCLAIMS:
I.
1. Was the Plaintiff, Delta, unjustly enriched by receiving payments from the Defendant, Wysong, for work that was not performed or costs that were not incurred in relation to work performed? YES
2. What amount, if any, should the Defendant, Wysong, recover of the Plaintiff, Delta, based upon unjust enrichment? $225.000
II.
1. Was the Defendant, Wysong, damaged by the negligence of the Plaintiff, Delta? Yes
2. What amount of damages has the Defendant, Wysong, sustained as a proximate result of any negligence? $9.000
Judge Lamm’s order and judgment was filed on 8 April 1997. On 14 April 1997, Judge Marvin K. Gray entered an order denying Delta’s motion for partial summary judgment and Wysong’s motion for summary judgment. Judge Gray’s order denied Wysong’s motion to amend its previously amended answer and counterclaim and declared all other motions moot. On 24 July 1997, Judge Lamm filed an order that denied Delta’s motions for judgment notwithstanding the verdict and for new trial. This order also denied Wysong’s motion to amend/alter the judgment but granted Wysong’s motion for a conditional new trial on the issue of damages in its unjust enrichment claim. Defendant and plaintiff appeal.
Wysong filed its notice of appeal on 8 August 1997, and Delta filed its notice of appeal on 15 August 1997. Wysong appeals from the 14 April 1997 order of Judge Gray denying their motion to amend, oral orders by Judge Lamm of 3 February 1997 allowing Delta’s motion for *165 directed verdict on several of Wysong’s negligence claims and dismissing Wysong’s claim for breach of contract, the order and judgment of 8 April 1997 taxing only a small portion of costs against Delta, and the order of 24 July 1997 granting a partial new trial on the issue of damages for Wysong’s unjust enrichment claim. Delta appeals from oral orders denying their motion for directed verdict and judgment notwithstanding the verdict on Wysong’s unjust enrichment claim. For similar reasons they appeal from the order and judgment of 8 April 1997, and they also appeal from the order of 24 July 1997 denying Delta’s motion for a new trial on Delta’s payment on account action.
Wysong first seeks reinstatement of the verdict granting Wysong damages for its unjust enrichment claim against Delta arguing that the trial court erred by setting aside the jury award. We disagree. It is well established that “[i]f there is a contract between the partiesf,] the contract governs the claim[,] and the law will not imply a contract.”
Booe v. Shadrick,
Wysong next argues that the trial court erred when it denied Wysong’s motion to amend its previously amended pleadings to include a claim for unfair or deceptive acts or practices in commerce. Motions to amend are governed by N.C. Gen. Stat. § 1A-1, Rule 15 (1990). Generally, Rule 15 is construed liberally to allow amendments where the opposing party will not be materially prejudiced.
See Members Interior Construction v. Leader Construction Co.
Inc.,
Wysong next assigns error to the trial court’s failure to tax Delta with the full costs. Taxing of costs is governed by Article 6 of the North Carolina General Statutes. N.C. Gen. Stat. §§ 6-18 and 6-19 (1986) detail certain actions where costs are allowed as a matter of course. Costs not allowed as a matter of course under sections 6-18 and 6-19 may be allowed in the court’s discretion under N.C. Gen. Stat. § 6-20 (1986). The court’s discretion under section 6-20
is not reviewable on appeal. See Minton v. Lowe’s Food Stores,
Wysong also argues that the trial court erred by not taxing Wysong’s attorneys’ fees against Delta. We disagree. “As a general rule[,] contractual provisions for attorney’s fees are invalid in the absence of statutory authority. This is a principle that has long been settled in North Carolina and fully reviewed by our Supreme Court . . . .”
Forsyth Municipal ABC Board v. Folds,
Wysong’s fourth argument is that the trial court erred when it granted Delta’s motion for a directed verdict on Wysong’s claim for breach of contract. In reviewing a directed verdict, this Court must determine whether the evidence taken in the light most favorable to the non-moving party is sufficient as a matter of law to be submitted to the jury.
See Davis v. Dennis Lilly Co.,
Wysong also argues that the trial court interpreted the contract in a manner contrary to law. Wysong claims that under the 1988 contract, Delta was obliged to fully delineate the extent of environmental contamination. The language of the contract undercuts this assertion. The contract states, “The proposed scope of work for the second phase is designed to ... better delineate the extent of the contaminant plumes from the identified sources,” (emphasis added). The trial *169 court interpreted the contract by its plain, unambiguous meaning. Delta’s responsibility was not to fully define the area of contamination. Rather, Delta only agreed to “better delineate” the scope of pollution. Because the trial court properly interpreted the contracts and because , this case is not appropriate for the “common knowledge” exception, we find no error in the trial court’s decision to grant Delta’s motion for directed verdict on Wysong’s breach of contract claim.
Wysong’s final argument is that the trial court erred when it entered a directed verdict as to several of Wysong’s negligence counterclaims. In reviewing the trial court’s decision on a motion for directed verdict, we must determine whether the evidence taken in the light most favorable to the non-moving party is sufficient as a matter of law to be submitted to the jury.
See Davis,
Except where otherwise provided by statute, a cause of action for malpractice arising out of the performance of or failure to perform professional services shall be deemed to accrue at the time of the occurrence of the last act of the defendant giving rise to the cause of action: . . . Provided nothing herein shall be construed to reduce the statute of limitation in any such case below three years. Provided further, that in no event shall an action be commenced more than four years from the last act of the defendant giving rise to the cause of action ....
Id.
The statute of repose created by section l-15(c), begins to run on the date of the “last act of the defendant giving rise to the cause of action.”
See Sharp v. Teague,
[T]he doctrine tolls the running of the statute for the period between the original negligent act and the ensuing discovery and *170 correction of its consequences; the claim still accrues at the time of the original negligent act or omission.
To benefit from this doctrine, a plaintiff must show both a continuous relationship with a physician and subsequent treatment from that physician. The subsequent treatment must consist of an affirmative act or an omission related to the original act, omission, or failure which gave rise to the claim.
We now affirm that the continuing course of treatment doctrine, only as set forth above, is the law in this jurisdiction.
Id.
at 137,
Thus, we must determine whether the action is timely under section l-15(c), more specifically, whether the action was commenced within “four years from the last act of the defendant giving rise to the cause of action.” N.C. Gen. Stat. § l-15(c) (1996). Wysong presented expert testimony in support of their negligence counterclaim. During cross-examination, Wysong’s expert testified as follows:
Q. Are you saying that what Delta did wrong was in connection with the design of the system?
A. Wasn’t necessarily the design of the system, it was the way the system was operated.
Q. Which is a consequence of the design of the system, is that right?
A. Design and/or installation.
Q. And, the design and/or installation of the system was complete as of the time of the spill, is that right?
A. That is correct.
*171 Q. Whatever it is that Delta did which was a departure from the standard of care, it did some time before the spill actually occurred, is that correct?
A. That is correct.
According to Wysong’s expert witness, no action after the spill was a departure from the standard of care. Therefore, any acts giving rise to the causes of action dismissed by the trial court occurred before the spill. Because the spill was discovered on 15 July 1991 and Wysong’s counterclaim was not filed until 27 September 1995, the dismissed counterclaims were not preserved within the statutory period prescribed by section l-15(c). Accordingly, Delta’s motion for directed verdict was properly granted.
We now turn to Delta’s appeal. As we have held that the contracts between Delta and Wysong bar Wysong’s unjust enrichment claim, we need not address Delta’s first three assignments of error. In its remaining assignment of error, Delta contends that the trial court improperly denied its motions for directed verdict, judgment notwithstanding the verdict, and a new trial. Delta bases its assignment of error on the contention that the jury’s verdict is contrary to law and the greater weight of the evidence. We disagree. Generally, the trier of fact, in this case the jury, must resolve issues of credibility and determine the relative strength of competing evidence.
See Upchurch v. Upchurch,
However, “[o]ur Supreme Court has recognized that proof of an injury to a party’s legal rights entitles that party to nominal damages at least.”
Cole v. Sorie,
In summary, the existence of valid contracts precludes Wysong’s action for unjust enrichment. The trial court’s determination that Wysong’s motion to amend came “rather late” in the case leads us to conclude that the motion was properly denied. Furthermore, as the instant case is not an exception to the general rule against enforcing contractual attorney’s fees clauses absent statutory authorization, we find no error in the trial court’s award of costs. The trial court properly interpreted the contracts between the parties, and because the instant case is not appropriate for the “common knowledge” exception, Delta’s motion for directed verdict was properly granted. In addition, we choose not to expand the “continuing course of treatment doctrine” to the providing of professional engineering services. Thus, Wysong’s negligence claims were properly dismissed. Finally, because the jury determines matters of weight and credibility afforded evidence and Wysong offered evidence that Delta’s billing methods were inaccurate, we find that the jury’s verdict is not contrary to the law as claimed by Delta. Therefore, we reverse in part and affirm in part and remand this case to the trial court for entry of judgment consistent with this opinion.
Affirmed in part, reversed in part and remanded.
