Commissioner may thenceforward recover interest on the sum then due at such rate not exceeding nine per centum per annum as he may deem fit.

Execution of work by occupier in default of owner and deduction of expenses from rent.— Whenever the owner of any land or building fails to execute any work which he is required to execute under this Act, or under any rule or bye-law made thereunder, the occupier (if any) of such land or building may, with the previous approval of the Commissioner, execute the said work and shall be entitled to recover from the owner the reasonable expenses incurred by him in so doing and may, without prejudice to any other right of recovery, deduct the amount thereof from the rent payable by him to the owner.