(1) No return, assessment (including supervision, appeal and rectification), notice, summons or other proceedings furnished, made or issued or taken or purported to have been furnished, made or issued or taken in pursuance of any of the provisions of this Act shall be invalid or shall be deemed to be invalid merely by reason of any mistake, defect or omission in such return, assessment, notice, summons or other proceedings, if such return, assessment, notice, summons or other proceedings are in substance and effect in conformity with or according to the intent, purposes and requirements of this Act.
(2) The service of any notice, order or communication shall not be called in question if the said notice, order or communication, as the case may be, has already been acted upon by the dealer or person to whom it is issued or which service has not been called in question at or in the earliest proceedings commenced, continued or finalized pursuant to such notice, order or communication.
(3) No order, including an order of assessment, supervision, revision or rectification passed under the provisions of this Act shall be invalid merely on the ground that the action could also have been taken by any other authority under any other provisions of this Act.