If at any time after the sanction of any building or work has been accorded, the Commissioner is satisfied that such sanction was accorded in consequence of any material misrepresentation or fraudulent statement contained in the notice given or information further under sections 333, 334 and 335, he may be order in writing cancel for reasons to be recorded such sanction and any building or work commenced, erected or done shall be deemed to have been commenced, erected or done without such sanction:
     Provided that before making any such order the Commissioner shall give reasonable opportunity to the person affected as to why such order should not be made.