Michigan § 257.1307a - Prohibited conduct.

A motor vehicle repair facility that is subject to this act, or a person that is an owner or operator of a motor vehicle repair facility that is subject to this act, shall not, directly or through an agent or employee, do any of the following:

(a) Charge for repairs that are in fact not performed.

(b) Perform repairs that are in fact not necessary, unless the customer insists that the facility perform the repair and disregards the facility's advice that the repair is unnecessary.

(c) Represent, directly or indirectly, that repairs are necessary when in fact they are not.

(d) Perform and charge for repairs that are not specifically authorized.

(e) Fail to perform promised repairs within the period of time agreed, or within a reasonable time, unless circumstances beyond the control of the facility prevent the timely performance of the repairs and the facility did not have reason to know of those circumstances at the time the contract was made.

(f) Represent, either directly or indirectly, that a replacement part used in the repair of a vehicle is new or of a particular manufacture when in fact it is used, rebuilt, reconditioned, deteriorated, or of a different manufacture, or otherwise fail to disclose in writing, before beginning a repair, the use of used, rebuilt, or reconditioned parts.

(g) Subsequent to a diagnosis requested by a customer for which a charge is made, fail to disclose a diagnosed or suspected malfunction, the recommended remedy for the malfunction, and any test, analysis, or other procedure employed to determine the malfunction.