Section 63. A person who is refused a certificate of competency, or whose certificate is revoked, may appeal from such decision to the issuing authority, who shall grant a rehearing of the case by a board of five examiners, no one of whom shall have acted as an examiner in the former instance; provided, that in the case of a person desiring to appeal from a refusal to issue to him a certificate of competency such appeal is accompanied by a fee to be determined annually by the commissioner of administration under the provision of section three B of chapter seven. Their decision shall be final if approved by head of said issuing authority.