(f)in any case where any export goods have been loaded without payment of export duty or in contravention of any provision of this Act or any other law for the time being in force relating to export of goods,-(i)such goods have been unloaded, or(ii)where the [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).] is satisfied that it is not practicable to unload such goods, the person-in-charge of the conveyance has given an undertaking, secured by such guarantee or deposit of such amount as the proper officer may direct, for bringing back the goods to India.