36. Repayment of tax

If it be proved to the satisfaction of the Collector that any person for any year of assessment has paid tax in excess of the amount with which he is properly chargeable, such person shall be entitled to have the amount so paid in excess refunded. Every claim for repayment under this section shall be made within 6 years from the end of the year of assessment to which the claim relates. The Collector shall certify the amount to be repaid and shall cause repayment to be made forthwith:

Provided that nothing in this section shall operate to extend or reduce any time limit for appeal or repayment specified in any other section or to validate any objection or appeal which is otherwise invalid, or to authorise the revision of any assessment or other matter which has become final and conclusive.