Cheated By Builder

I have bought a ready to move apartment in April, 2013 and I have given my part on time and rest was financed from bank by builder banker but he didn't accept that. And he is asking extra money for which I was not ready as loan was sanction and he didn't take the cheque and then he said again to reissue the cheque and I did the same and second loan sanction but this time again he's asking too much money. He didn't send any demand letter and then he took many maintenance cost and gave a possession letter and received the registration fees and stamp duty cost. I am not living in india and now he is saying that he's cancelled my apartment but he didn't send any notification to me. He mishaved with my mother and sister when they visited his office. I have already filed two RTI to get the complete information but he didn't respond anything. I have complaint three times to external affair of india and they directed to SSP Ghaziabad to take some action but nobody is helping me. Can someone help me out how can I over come this problem? I would highly obliged you.