All charges made by any warehouseman subject to the provisions of ORS 586.210 to 586.730, for the handling or storage of grain shall be just, fair and reasonable; and the State Department of Agriculture, upon the complaint of any person interested or by inquiry upon its own motion, after a full hearing, may:
(1) Declare any existing charge for the handling or storage of grain or any regulation whatsoever affecting such charge, or the receipt, handling or storage, to be unreasonable or unjust; and(2) Declare and order what is a just and reasonable charge or regulation to be imposed or enforced in place of that found to be unreasonable or unjust.