If any seller or sales finance company, in the making or collection of an installment contract, shall, directly or indirectly, contract for, take, or receive charges in excess of those authorized by the Nebraska Installment Sales Act except as a result of an accidental and bona fide error such contract shall be void and uncollectible as to (1) all of the excessive portion of the time-price differential, (2) the first one thousand dollars of the time-price differential authorized by section 45-338, and (3) the first four thousand dollars of the principal of the contract. If any seller or sales finance company violates any provision of the act, other than the violations described above, except as a result of an accidental and bona fide error, such installment contract shall be void and uncollectible as to the first five hundred dollars of the time-price differential and the first one thousand dollars of the principal of such contract. If any of such money has been paid by the buyer, such buyer or his or her assignee may recover under the act in a civil suit brought within one year after the due date, or any extension thereof, of the last installment of the contract.