The Authority or the Appellate Authority may amend any order passed by it under section 98 or section 101, so as to rectify any error apparent on the face of the record, if such error is noticed by the Authority or the Appellate Authority on its own accord, or is brought to its notice by the concerned officer, the jurisdictional officer, the applicant or the appellant within a period of six months from the date of the order:
         Provided that no rectification which has the effect of enhancing the tax liability or reducing the amount of admissible input tax credit shall be made unless the applicant or the appellant has been given an opportunity of being heard.