Except as otherwise expressly provided by law, knowingly permitting or offering to make or making any contract of life insurance, life annuity or accident and health insurance, or agreement as to such contract other than as plainly expressed in the contract issued thereon, or paying or allowing, or giving or offering to pay, allow, or give, directly or indirectly, as inducement to such insurance, or annuity, any rebate of premiums payable on the contract, or any special favor or advantage in the dividends or other benefits thereon, or any valuable consideration or inducement whatever not specified in the contract is an unfair method of competition.