Michigan Compiled Laws, Chapter 445. Trade and Commerce § 445.833

Sec. 3. (1) Except as otherwise provided in this section and before repairing, servicing, or performing maintenance on an appliance, a service dealer shall make a written estimate of the cost of the repair, service, or maintenance. The written estimate shall comply with subsection (2). The customer shall approve the estimate by signing the estimate, verbally approving the estimate via the telephone, or by any other equivalent method. If the customer approves the estimate by means of a telephone call or other equivalent method, the service dealer shall so indicate on the estimate and shall, if possible, obtain the customer's signature on the estimate at a later time. A service dealer shall not charge in excess of 110% of the amount noted in the written estimate unless the service dealer receives the verbal or written permission of the customer.

(2) A written estimate or attached documentation shall provide all of the following:

(3) A service dealer may charge a fee, as indicated in the written estimate, for any labor performed in examining the appliance and diagnosing any problems. If the appliance would require dismantling as part of the diagnosis, the service dealer shall include in the written estimate of the cost of dismantling and reassembling the appliance and the cost, if any, of any parts that would be destroyed or rendered inoperable by the dismantling and reassembly of the appliance.

(4) This act does not prohibit a service dealer from charging for a service call.

(5) This act does not prohibit a service dealer from combining the written estimate with the final bill described in section 5  1 into the same document.