(4)No proceedings shall be initiated under sub-section (1) or sub-section (2) in respect of any decision or order after the expiry of a period of six months from the date of communication of such decision or order:Provided that in respect of any decision or order passed before the commencement of the Customs and Central Excises Laws (Amendment) Act, 1987, the provisions of this sub-section shall have effect as if for the words six-months , the words one year were substituted.