California Code, Civil Code - CIV § 1747.60

(a) Every retailer shall correct any billing error made by the retailer within 60 days from the date on which an inquiry concerning a billing error was mailed.

(b) Any retailer who fails to correct a billing error made by the retailer within the period prescribed by subdivision (a) shall be liable to the cardholder in the amount by which the outstanding balance of the cardholder's account is greater than the correct balance, and any interest, finance charges, service charges, or other charges on the obligation giving rise to the billing error.

(c) Any cardholder who is injured by a willful violation of this section may bring an action for the recovery of damages. Judgment may be entered for three times the amount at which actual damages are assessed. The cardholder shall be entitled to recover reasonable attorney's fees and costs incurred in the action.

(d) As used in this section, an “inquiry” is a writing which is posted by mail to the address of the retailer, unless another address is specifically indicated by the retailer for the purpose of mailing inquiries with respect to billing errors, then to such address.