Notice required. No agent, broker or other representative or employee of any insurance company shall recommend, advise, suggest or require the cancellation of any insurance policy of the insurer which he represents, or of any other insurer at any time other than the policy anniversary or expiration date, unless he informs the insured in writing of the additional cost of such cancellation before the insured is requested or required to take action to cancel or terminate the policy which is then in force.