Mich. Comp. Laws § 462.42

Sec. 42. All claims against any common carrier for loss or damage to property from any cause, or for over-charge upon any shipments, or for any other service, if not acted upon within 90 days from the date of filing of such claim with the common carrier may be investigated by the commission in its discretion, and the result of such investigation may be embodied in a special report and the next annual report of the commission.