(a) Prior to transaction of any warehouse business at any warehouse under this article and annually thereafter, the warehouseman shall file with the Commissioner a schedule of charges to be made by the warehouse. All charges and regulations affecting such charges made by any warehouse licensed under this article for the storage of agricultural products shall be just, fair, and reasonable. No additional charge shall be made by any such warehouse other than as specified in its filed schedule. No change shall be made in a filed schedule of charges during a current year unless the Commissioner consents thereto. Any upward revision of charges of any such warehouse during any current year shall be applicable only to products received at such warehouse or services performed pursuant to instructions received from the storer after the Commissioner's approval of the upward revisions.

(b) Notwithstanding the provisions of subsection (a) of this Code section, any warehouseman under this article may establish and charge special rates as required by contract with the United States, or any agency of or corporation controlled by the United States, and none of the restrictions or requirements of subsection (a) of this Code section shall apply to such rates.

(c) No warehouseman shall make any charge for any service unless he has then on file a schedule of charges to be made by the warehouse for that service.

(d) No warehouseman shall make a duplicate collection of tariff charges for the first month's service of the warehouseman. It is the intent and purpose of this Code section to prevent a duplication of the collection of such charges in any manner or fashion.