California Code, Business and Professions Code - BPC § 9844

An initial written estimate for the cost of repair shall be given to the customer before performing any repairs.  The written estimate shall include all costs for parts and labor, and the service dealer may not charge for work done or parts supplied in excess of the estimate without the previous consent of the customer.  The service dealer may charge a reasonable fee for services provided in determining the nature of the malfunction in preparation of a written estimate for repair.  The service dealer shall advise the customer in writing of the amount of the fee prior to a repair made in the residence, before removal of the consumer goods from the customer's residence, or upon acceptance of the goods at the repair facility or registered location.  This section shall not prohibit the use of a written estimate in an electronic format.