Cal. Civ. Code § 1789.134
(a) A consumer credit reporting agency, creditor, debt collector, or debt buyer that knows that a consumer is represented by a credit services organization, and that also has knowledge of, or can readily ascertain the credit services organization’s name and address shall communicate with the credit services organization unless either of the following circumstances apply:
(b) Notwithstanding subdivision (a), a consumer credit reporting agency, creditor, or debt collector shall not be required to communicate with a credit services organization concerning an account that is subject to a dispute if any of the following apply: