Cal. Civil Code § 1793.6

Except as otherwise provided in the terms of a warranty service contract, as specified in subdivision (a) of Section 1793.2, entered into between a manufacturer and an independent service and repair facility, every manufacturer making express warranties whose consumer goods are sold in this state shall be liable as prescribed in this section to every independent serviceman who performs services or incurs obligations in giving effect to the express warranties that accompany such manufacturer’s consumer goods whether the independent serviceman is acting as an authorized service and repair facility designated by the manufacturer pursuant to paragraph (1) of subdivision (a) of Section 1793.2 or is acting as an independent serviceman pursuant to subdivisions (c) and (d) of Section 1793.3. The amount of such liability shall be an amount equal to the actual and reasonable costs of the service and repair, including any cost for parts and any reasonable cost of transporting the goods or parts, plus a reasonable profit. It shall be a rebuttable presumption affecting the burden of producing evidence that the reasonable cost of service or repair is an amount equal to that which is charged by the independent serviceman for like services or repairs rendered to service or repair customers who are not entitled to warranty protection. Any waiver of the liability of a manufacturer shall be void and unenforceable.