(a) the manager of the hotel or the owner of the lodging house, as the case may be, shall not charge any amount in excess of the fair rate and shall not, except with tile previous Written permission of the Rent Authority, withdraw from the lodger any concession or services allowed at the time when Me Relic Authority determined the fair rate;

(b) any agreement for the payment of any charges in excess of such fair rate shall be void in respect of such excess and shall be construed as if it were an agreement for payment of the said fair rate;

(c) any sum paid' by a lodger in excess of the fair rate shall be recoverable by him at any time within a period of six months from the date of the payment from the manager of the hotel or the owner of the lodging house or Ills legal representatives and may, without prejudice to any other mode of recovery, be deducted by such lodger from any amount payable by him to such manager or owner.