Cal. Civ. Code § 2984
Any failure to comply with any provision of this chapter (commencing with Section 2981) may be corrected by the holder, provided, however, that a willful violation may not be corrected unless it is a violation appearing on the face of the contract and is corrected within 30 days of the execution of the contract or within 20 days of its sale, assignment or pledge, whichever is later, provided that the 20-day period shall commence with the initial sale, assignment or pledge of the contract, and provided that any other violation appearing on the face of the contract may be corrected only within such time periods. A correction which will increase the amount of the contract balance or the amount of any installment as such amounts appear on the conditional sale contract shall not be effective unless the buyer concurs in writing to the correction. If notified in writing by the buyer of such a failure to comply with any provision of this chapter, the correction shall be made within 10 days of notice. Where any provision of a conditional sale contract fails to comply with any provision of this chapter, the correction shall be made by mailing or delivering a corrected copy of the contract to the buyer. Any amount improperly collected by the holder from the buyer shall be credited against the indebtedness evidenced by the contract or returned to the buyer. A violation corrected as provided in this section shall not be the basis of any recovery by the buyer or affect the enforceability of the contract by the holder and shall not be deemed to be a substantive change in the agreement of the parties.
Ca. Civ. Code § 2984