4. No certificate of registration, demonstrator number or number plate shall be suspended or revoked, civil penalty imposed or authority to issue temporary registrations suspended until such registrant shall have been given the opportunity to be heard, upon written notice to the registrant, before an officer or employee of the department designated for such purpose by the commissioner. However, the commissioner may temporarily suspend a registration, demonstrator numbers or number plates and/or the authority to issue temporary registrations pending a hearing. Upon the denial of an application for a certificate of registration, the applicant shall, upon written request made within ten days after the applicant is notified of such denial, be entitled to a hearing before an officer or employee of the department designated for such purpose by the commissioner.