(1) Upon complaint in writing by any person, firm, corporation, association, mercantile, agricultural or manufacturing society, or by any body politic, municipal organization, or motor carrier, that any of a motor carrier of household goods‘ rates, fares, charges, or classifications, or any joint rate or rates of any motor carrier of household goods are unreasonable or unjustly discriminatory or otherwise in violation of this act, or that any practice affecting the transportation of property by a motor carrier or any service in connection with the transportation of property is unreasonable or unjustly discriminatory, or that any service of a motor carrier of household goods is inadequate, or that this act or any order, rule, or practice established by the commission applicable to a motor carrier of household goods, or charges filed with the commission by a motor carrier of household goods, has been violated or deviated from, or is being violated or deviated from by a motor carrier; or upon a complaint against a motor carrier of household goods that this act or any order, rule, or practice established by the commission applicable to the motor carrier of household goods has been violated or deviated from, or is being violated or deviated from, the commission shall notify the parties complained of that a complaint has been made, and shall furnish a copy of the complaint with the notice, and 20 days after the notice has been given, the commission may proceed to investigate the complaint as provided in this section. Only the commission, on its motion, may bring a complaint against a motor carrier of household goods for predatory rates, practices, or rules under section 6(1) of article III. Before investigating a complaint, the commission shall give the motor carrier and the complainants at least 10 days’ notice of the time and place when and where the matters will be considered and determined, and the parties are entitled to be heard and shall have process to enforce the attendance of witnesses. If, upon investigation of a motor carrier of household goods, any matters complained of are found to be in violation of this act, the commission shall determine and by order fix the practice, service, or charges and shall order a substitute practice, service, or charge that conform to this act and the rules of the commission applicable to the motor carrier of household goods. The order shall further direct the parties complained of to cease and desist from the violation and conform to the terms of the order. The commission shall deliver a certified copy of the order to the affected parties. The order shall of its own force take effect and become operative 20 days after service. All motor carriers of household goods to which the order applies shall, on or before the date the order becomes effective, make changes in schedules on file as necessary and make changes in their practices, services, or minimum rates as necessary to conform to the order. Certified copies of all other orders of the commission shall be delivered to the parties affected in like manner and, unless otherwise prescribed in this act, shall take effect at the time the commission prescribes.

    (2) If the commission believes that this act or any rule or order of the commission made under this act has been or is being violated, or that any charges have been made or collected or service performed in violation of this act or any rule or order of the commission made under this act, and that an investigation relating to the violation should be made, the commission may on its own motion or on the application of anyone investigate the suspected violation. Before making the investigation, the commission shall present to the parties alleged to be guilty of the violations a written statement setting forth the matters to be investigated. After the commission has presented the written statement described in this subsection, on 10 days’ notice to the parties of the time and place of the investigation, the commission may investigate the matters complained of and enter orders as provided for an investigation upon complaint under subsection (1). An investigation, inquiry, or hearing that the commission has power to undertake or to hold may be undertaken or held by or before any commissioner or any employee of the commission when directed by the commission or its chairperson. The commissioner or employee shall submit findings of fact and conclusions of law to the commission. If the findings of fact and conclusions of law are approved and confirmed by the commission and ordered filed in its office, they shall be the decision and the order of the commission. All investigations, inquiries, or hearings of a commissioner or an employee are considered as the investigation, inquiry, and hearing of the commission.