3.—(1) If the person on whom a completion notice is served agrees in writing with the Department that a day specified by the agreement shall be the completion day in relation to the building, that day shall be the completion day in relation to it.N.I.
(2) Where such an agreement as is mentioned in sub-paragraph (1) is made, the completion notice relating to the building shall be deemed to have been withdrawn.
4.—(1) A person on whom a completion notice is served may, not later than twenty-eight days from the date of service on him of the notice, appeal to the Commissioner against the notice on the ground that the building to which the notice relates has not been or, as the case may be, cannot reasonably be expected to be completed by the day stated in the notice.N.I.
(2) Where a person appeals against a completion notice and the appeal is not abandoned or dismissed, the completion day shall be such day as the Commissioner shall determine.
5. Where a completion notice is not withdrawn and no appeal under paragraph 4 is brought against the notice or any appeal under that paragraph is abandoned or dismissed, the day stated in the notice shall be the completion day in relation to the building.]N.I.