Before the examining board takes any disciplinary action against any professional land surveyor, it shall give the licensee a hearing on the matter and shall, at least twenty days prior to the date set for the hearing, notify such licensee in writing. Such notice shall contain an exact statement of the charges against the professional land surveyor and the date and place of hearing. The licensee shall be heard in person or by counsel before an examiner appointed by the examining board in reference to such charges. Such notice may be served by delivering it personally to the licensee or by sending it by either registered or certified mail addressed to the licensee’s last-known business address as shown by the professional land surveyor’s license.