Any insurer or advisory organization aggrieved by any order or decision of the commissioner made without a hearing, within thirty days after notice of the order to the insurer or organization, may make written request to the commissioner for a hearing thereon. The commissioner shall hear the party within twenty days after receipt of the request and shall give not less than ten days’ written notice of the time and place of the hearing. Within fifteen days after the hearing, the commissioner shall affirm, reverse, or modify the previous action, specifying the reasons therefor. Pending the hearing and decision thereon the commissioner may suspend or postpone the effective date of the previous action. This chapter does not require the observance at any hearing of formal rules of pleading or evidence.