Section 57. The commissioner and his duly authorized assistants shall have authority to enforce sections fifty-two to sixty, inclusive, and to prosecute all violations thereof. Before any prosecutions by the commissioner or any of his duly authorized assistants, the parties concerned shall be given an opportunity to be heard before the said commissioner or a person designated by him for such purpose. The parties concerned shall be given reasonable notice of hearing specifying the day, hour and place thereof and accompanied by a description of the alleged violation.