(l) (1) Notwithstanding any other provision of law, when the department serves a notice of violation to correct and certify a condition that constitutes a violation of article fourteen of subchapter two of this chapter, the notice of violation shall specify the date by which the violation shall be corrected, which shall be twenty-one days after service of the notice of violation for a class C violation and thirty days after the service of the notice of violation for a class B violation, and the procedure by which the owner, for good cause shown pursuant to this subdivision, may request a postponement. The notice of violation shall further specify that the violation shall be corrected in accordance with the work practices established in accordance with section 27-2056.11 of this code. The notice of violation shall be served by personal delivery to a person in charge of the premises or to the person last registered with the department as the owner or agent, or by registered or certified mail, return receipt requested, or by certified mail with proof of delivery, to the person in charge of the premises or to the person last registered with the department as the owner or agent; provided that where a managing agent has registered with the department, such notice of violation shall be served on the managing agent. Service of the notice of violation shall be deemed completed three days from the date of mailing. Notification, in a form to be determined by the department, of the issuance of such violation shall be sent simultaneously by regular mail to the occupant at the dwelling unit that is the subject of such notice of violation. The department may postpone the date by which a violation shall be corrected upon a showing, made within the time set for correction in the