Whenever after full hearing upon a complaint made as provided in section 210 of this title, or after full hearing under an order for investigation and hearing made by the Secretary on his own initiative, either in extension of any pending complaint or without any complaint whatever, the Secretary is of the opinion that any rate, charge, regulation, or practice of a stockyard owner or market agency, for or in connection with the furnishing of stockyard services, is or will be violative of section 205, 206, or 208 of this title, the Secretary - (a) May in accordance with the standard set forth in section 206 of this title determine and prescribe what will be the rate or charge, or rates or charges, to be thereafter in such case observed as the maximum or minimum or both to be charged, and what regulation or practice is or will be just, reasonable, and nondiscriminatory to be thereafter followed: Provided, That the Secretary shall prescribe the rate or charge, or rates or charges, on a percentage or per head basis at the election of the stockyard owner or market agency, or on any other basis elected by the stockyard owner or market agency unless the Secretary finds such other basis to be violative of section 206 of this title; and (b) May make an order that such owner or operator (1) shall cease and desist from such violation to the extent to which the Secretary finds that it does or will exist; (2) shall not thereafter publish, demand, or collect any rate or charge for the furnishing of stockyard services other than the rate or charge or rates or charges so prescribed; and (3) shall conform to and observe the regulation or practice so prescribed.