129   Revocation or variation of notices or directions

(1)  A notice or direction under this Act may be revoked or varied by a subsequent notice or notices or direction or directions.

(2)  A notice or direction may be varied by modification of, or addition to, its terms and specifications.

(3)  Without limiting the above, a notice or direction may be varied by extending the time for complying with the notice or direction.

(4)  A notice or direction may only be revoked or varied by the authority or person that gave it and in the manner required for the giving of the notice or direction.