Whenever, after full opportunity for hearing, upon a complaint or under an order for investigation and hearing made by the Commission
on its own initiative, the Commission
shall be of opinion that any charge, classification, regulation, or practice of any carrier
is or will be in violation of any of the provisions of this chapter, the Commission
is authorized and empowered to determine and prescribe what will be the just and reasonable charge or the maximum or minimum, or maximum and minimum, charge or charges to be thereafter observed, and what classification, regulation, or practice is or will be just, fair, and reasonable, to be thereafter followed, and to make an order that the carrier
shall cease and desist from such violation to the extent that the Commission
finds that the same does or will exist, and shall not thereafter publish, demand, or collect any charge other than the charge so prescribed, or in excess of the maximum or less than the minimum so prescribed, as the case may be, and shall adopt the classification and shall conform to and observe the regulation or practice so prescribed.