81. Review-

Subject to such rules as may be made by the State Government under this Act any authority appointed under Section 4 or the Tribunal may review any order passed by it, if such review is, in the opinion of the said authority or Tribunal, as the case may be, necessary on account of a mistake which is apparent from the record;

Provided that no such review, if it has the effect of enhancing the tax or penalty or both, or of reducing a refund shall be made unless the said authority or the Tribunal, as the case may be, has given the dealer, or the person concerned, a reasonable opportunity of being heard.