Claim for damages caused by tenant to furniture and fixtures.

Dear Sir, I gave my flat in for rent for Rs. 10500/- per month with a month security deposit with a rental agreement. In the agreement, the rent is mentioned as Basic Rent Rs.6 000/, Rent for furniture Rs. 4500/-. Total rent Rs. 10500/-. Tenant has stayed in flat for three years and recently vacated. However, I discovered that there are lots of damages to the furniture. The tenant used the water purifier continuously for three years without servicing it. Due to this, two filters and the motor got damaged. The water heater was not serviced and hence its heating coil needed replacement. While vacating the flat, the tenant did not even clean the house. He left the flat without doing fixing any of the damages. The total cost of cleaning the flat, repairs, Rs. 12535/-. He is refusing to pay any of these damages. He says that since the rent for furniture is also part of the rent, then the damages caused is not his responsibility and he is pressing me to pay deposit. What should I do?