If after 30 days following the giving of the notice mentioned in Section 1620.3 the insurer has failed to cease making, issuing, or circulating such false misrepresentations or causing the same to be made, issued or circulated in this State, and if the commissioner has reason to believe that a proceeding by him in respect to such matters would be to the interest of the public, and that the insurer is issuing or delivering contracts of insurance to residents of this State or collecting premiums on such contracts or doing any of the acts enumerated in Section 1620.5, he shall take action against the insurer under the Unfair Trade Practice Act.