(a) Orders and notices of the Commissioner shall be effective only when they are in writing and signed by him or by his authority.

(b) Every such order shall state its effective date and shall state concisely:

(1) Its intent or purpose;

(2) The grounds on which it is based; and

(3) The provisions of this title pursuant to which action is taken or proposed to be taken; but failure to designate any provision shall not deprive the Commissioner of the right to rely thereon.

(c) An order or notice may be served by delivery to the person to be ordered or notified or by mailing it, postage prepaid, addressed to him at his principal place of business or last address of record in the Commissioner's office.