Our owner is not giving our security money back.

On march 27 february we contact with our previous owner. We both agreed to living on rent at our owner property house in noor city.we both agreed at that time.so we shifted on 1 march at night.after living one month there first there was water problem in society so he told us to bring water tank n pay them he will deduct money from the rent.but at the time we came to know about that our maintenance rent is Rs 1000 and he is taking Rs 1500 with us but still he didnt to that. So on the month of april , he started to build 3rd floor on top of our house without letting us know. So we told him to stop only for 2 weeks so we can give our final exams and he can finish his after that because our exams were near. He still didnt take any actions and and the work is going . So when he came back n shouting at us saying ," why you guys stopping my house work , who give you permission for that" So he was i will thrown you all out right now , so we said that we have already deposit rent to you with electricity bill but somehow we managed to keep him calm. But the construction was not stopped and still going on so we all students decides to left the house we rold thw owner to left the house one month before he told us ok and even we left the house 2 days before. But at the time of ending when we ask him to give our security deposit back he is not giving any response to us. Everytime he used to say he is out of state and at late night he will come back n talk everything about n deduct money and give rest of the deposit but he never comes we even call everyday more than 10 times he is not giving back our security money so sir you tell us what can we do now? He didnt even make any agreement.