No workers' compensation insurer or officer or agent thereof or insurance broker or solicitor shall represent, either orally or in writing, as an inducement either to insure or to continue or to renew insurance, that the insurer has agreed or will agree (a) to pay a specified policyholder's dividend or (b) upon a formula, criteria or factors which set forth or can be used to determine the amount of dividend, or percentage of premium to be paid as dividend, or amount or percentage of premium to be retained by the insurer after payment of dividend or (c) to pay a dividend by any plan which is unfairly discriminatory.