Landlord not returning deposit honestly

Respected Sir, I'm Chintan living in pune, maharashtra. We are four friends came in pune 6th August, 2014 to study. We took a 1BHK flat in yerwada, pune. Our landlord is Mr.Kumar. We gave 20000 Rs. deposit and 10000 Rs. rent. Every month landlord's nephew collect rent and light-bill. So at the starting of November when he came for rent we inform him to leave flat next month that is end of November, and also text message on 18th November to landlord. After leaving when we call to landlord for deposit, he cant response us and talking us with bad words, and said you inform me on 18th so i'll give you on 18th December. we recorded it on phone. now he is ready to pay only 6000 Rs. He charged 4000 Electricity bill, 10000 for informing late. As per agreement and police verification our landlord is Mr. Raju but whenever we had any trouble in flat he said to inform to Mr. Kumar who is landlord. When we go to police station they said its not our case, solve your own. Please help us what we take action against him. Regards, Chintan