Statutes prohibit any trade practice which is defined in this act or determined pursuant to this act to be an unfair method of competition or an unfair or deceptive act or practice in the business of insurance. The commissioner shall have power to examine and investigate into the affairs of every person engaged in the business of insurance in this State in order to determine whether such person has been or is engaged in any unfair method of competition or in any unfair or deceptive act or practice prohibited by section three of this act.