(3)When any person is expressly or impliedly authorised by the owner, importer or exporter of any goods to be his agent in respect of such goods for all or any of the purposes of this Act, such person shall, without prejudice to the liability of the owner, importer or exporter, be deemed to be the owner, importer or exporter of such goods for such purposes:Provided that where any duty is not levied or is short-levied or erroneously refunded on account of any reason other than any wilful act, negligence or default of the agent, such duty shall not be recovered from the agent unless in the opinion of [Assistant Commissioner of Customs or Deputy Commissioner of Customs] [ Substituted by Act 27 of 1999, Section 100, for " Assistant Commissioner of Customs" (w.e.f. 11.5.1999). Earlier, these words were substituted by Act 22 of 1995, Section 50 (w.e.f. 26.5.1995).] the same cannot be recovered from the owner, importer or exporter.