No contract between the department and the prepaid health plan shall be amended without the public notice and if necessary the holding of a public hearing as required in Section 14300 if such amendments make any of the following changes in the contract:

1. (a) Reduction in the scope or availability of services.
2. (b) Enlargement of the service area.
3. (c) Increase in the maximum enrollment permitted under the contract.
4. (d) Any other change in the plan’s organization, operation, or delivery of services which the director determines will have a substantial impact on the ability of enrollees to obtain health care services.