Any interested person shall have the right to have the department call a hearing for the purpose of taking action with respect to any matter within the jurisdiction of the department by filing a verified written petition therefor, which shall state in substance the matter and reasons for and nature of the action requested. Upon receipt of any such request the department, if in its judgment a hearing is warranted and justifiable, shall promptly call a hearing thereon, and after such hearing, and with all convenient speed, and in any event within twenty days after the conclusion of such hearing, shall take such action with regard to the subject matter thereof as it may deem appropriate.