TDS on Rent

Our company has taken a premises on rent for office. But the agreement has been designed in such a way that in the agreement it is no where mentioned that the owner will charge rent for the premises, rather in its place term "Service Charges for premises" has been mentioned. Now owner insisting that tax should not be deducted @ 20% (for rent) rather a lesser rate should be applied on the transactions. It is to be noted that premises is fully furnished and additionally we have to pay amount for extra hours of work beyond the time limit to the owners.