(n)with the sanction of the Chief Commissioner any other tax, toll, rate or fee; provided-(i)that both the taxes mentioned in clauses (a) and (f) shall not be imposed in respect of the same premises;(ii)that when the Board has taken a loan from or guaranteed by the Chief Commissioner, the Board shall not, without the previous sanction of the Chief Commissioner, make any alteration in respect of any tax which may have the effect of reducing the income of the Board; and(iii)the Chief Commissioner may, by order, exempt from the payment of any rate, tax, toll or fee payable under the provisions of this Act, any diplomatic or consular mission of a foreign state and the diplomatic and consular officers of such mission.