(a) Before proceeding with preparing an estimate, the shop shall do both of the following:
(1) Disclose to the customer the amount, if any, of the charge for preparing the estimate.
(2) Obtain a written authorization to prepare an estimate if there is a charge for that estimate.
(b) It is a violation of this Article for any motor vehicle repair shop to require that any person waive his or her rights provided in this Article as a precondition to the repair of his or her vehicle by the shop or to impose or threaten to impose any charge which is clearly excessive in relation to the work involved in making the price estimate for the purpose of inducing the customer to waive his or her rights provided in this Article.