Every commission merchant shall retain a copy of all records covering each transaction for a period of three years from the date thereof, which copy shall at all times be available for, and open to, the confidential inspection of the director and the consignor, or authorized representative of either. In the event of any dispute or disagreement between a consignor and a commission merchant arising at the time of delivery as to condition, quality, grade, pack, quantity, or weight of any lot, shipment, or consignment of agricultural products, the department shall furnish, upon the payment of a reasonable fee therefor by the requesting party, a certificate establishing the condition, quality, grade, pack, quantity, or weight of such lot, shipment, or consignment. Such certificate shall be prima facie evidence in all courts of this state as to the recitals thereof. The burden of proof shall be upon the commission merchant to prove the correctness of his or her accounting as to any transaction which may be questioned.