(1) Where the Rent Tribunal has fixed fair rent or a building, the landlord shall not claim, receive or stipulate for the payment of—
(a) any extra sum in addition to such fair rent, or
(b) save as provided in section 13 or section 14, anything in excess of such fair rent:
Provided that the landlord may claim, receive or stipulate for the payment of an amount not exceeding one month’s rent, by way of advance.
(2) Save as provided in sub-section (1), any extra sum or any rent paid in addition to, or in excess of, such fair rent, whether before or after the commencement of this Act, in consideration of the grant, continuance or renewal of the tenancy of the building, shall be refunded by the landlord to the person by whom it was paid or, at the option of such person, shall be otherwise adjusted by the landlord:
Provided that where before the determination of the fair rent, has been paid in excess hereof, the refund or adjustment shall be limited to the amount paid in excess for a period of six months prior to the date of the application by the tenant or the landlord under sub- -section (1) of section 12 for fixing the fair rent.
(3) Any stipulation in contravention of sub-section (1) or sub-section (2) shall be void.