Sufficient service of any process in any action brought under this Act may be made by serving a copy thereof with the agency designated to receive process in the disclosure statement filed with the Administrator or in the absence of such agent at the principal business address set forth in the disclosure statement. Where no disclosure statement has been filed and personal jurisdiction cannot otherwise be obtained in this State over a person who engaged in conduct prohibited or made actionable by this Act or any rule or order hereunder, that conduct shall be considered equivalent to the appointment of the Administrator to be such person’s attorney to receive service of any lawful process in any noncriminal suit, action or proceeding against him or his successor, executor, or administrator which grows out of that conduct and which is brought under this Act or any rule or order hereunder, with the same force and validity as if served on him personally. Service may be made by leaving a copy of the process in the office of the Administrator, but it is not effective unless (a) the plaintiff forthwith sends notice of the service and a copy of the process by registered or certified mail to the defendant or respondent at his last known address or takes other steps which are reasonably calculated to give actual notice and (b) the plaintiff’s affidavit of compliance with this Section is filed in the case on or before the return day of the process, if any, or within such further time as the court allows.