The Department may upon its own motion and shall upon the verified complaint in writing of any person, setting forth facts which, if proved, would constitute grounds for refusal, suspension or revocation under this Act, investigate the actions of any applicant or any person or persons holding or claiming to hold a license. The Department shall, before refusing to issue or renew, and before suspension or revocation of a license, at least 10 days prior to the date set for the hearing, notify in writing the applicant for or holder of a license, hereinafter called the respondent, that a hearing will be held on the date designated to determine whether the respondent is privileged to hold such license, and shall afford the respondent an opportunity to be heard in person or by counsel with reference thereto. Such written notice may be served by delivery of the same personally to the respondent, or by mailing the same by registered or certified mail to the place of business last theretofore specified by the respondent in the last notification to the Department. At the time and place fixed in the notice, the Department shall proceed to hear the charges and both the respondent and the complainant shall be accorded ample opportunity to present in person or by counsel such statements, testimony, evidence and argument as may be pertinent to the charges or to any defense thereto. At such hearing, the Director or the person designated by the Director of the Department may administer oaths.