(1) Subject to the provisions of this Act, where, at any time after the commencement of this Act, the rent of any premises to which this Act applies exceeds the standard rent by more than the amount permitted under this Act, the amount of such excess shall, despite any agreement or lease made before or after the commencement of this Act to the contrary, be irrecoverable from the lessee, and if it is paid by the lessee, shall be recoverable by him or her, or by persons claiming through him or her from the person to whom it was paid or his or her personal representative, and may, with prejudice to any other method of recovery, be deducted from any rent or money due or subsequently becoming due from the lessee. However, in the case of premises leased at the commencement of this Act under a tenancy agreement or lease made before the commencement of this Act, this subsection does not operate to render irrecoverable from the lessee or recoverable by the lessee or persons claiming through him or her, or deductible, any rent payable under the tenancy agreement or lease save and in so far as it is in excess of the rent which immediately prior to the commencement of this Act was permissible under the Rent Restriction Act, 1943.