Cal. Civil 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: (1) The credit services organization fails to respond within 30 days to a communication from a consumer credit reporting agency, creditor, debt collector, or debt buyer. (2) The consumer expressly directs the consumer credit reporting agency, creditor, debt collector, or debt buyer not to communicate with the credit services organization. (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: (1) The account subject to the dispute has been paid, settled, or otherwise resolved and has been reported as paid, settled, or otherwise resolved on the consumer’s credit report. (2) The account subject to the dispute has been removed from the consumer’s credit report. (3) The debt collector has provided to the credit services organization or to the consumer the verification information or documentation described in Section 1692g(b) of Title 15 of the United States Code regarding the account subject to dispute. (4) The debt buyer has provided to the credit services organization or to the consumer the information or documentation described in subdivisions (a) and (b) of Section 1788.52 regarding the account subject to the dispute. (5) The consumer credit reporting agency, creditor, or debt collector reasonably determines that the dispute is frivolous or irrelevant pursuant to Section 1681i(a)(3) or Section 1681s-2(a)(1)(F) of Title 15 of the United States Code.