No manufacturer of motor vehicles, distributor, distributor branch or factory branch or officer, agent or other representative thereof shall fail to compensate adequately and fairly its dealer or representative for labor, parts or expenses incurred by the dealer or representative with regard to factory warranty agreements performed by the dealer or representative. In no event shall said manufacturer of motor vehicles, distributor, distributor branch or factory branch pay to its dealer or representative a labor rate per hour for warranty work less than that charged by said dealer or representative to its retail customer. Conversely, no franchised dealer or representative shall charge its manufacturer, distributor, distributor branch or factory branch a labor rate per hour in excess of the rate charged its retail customers.