Refund of booking amount from builder

Good Day Sir, My father in law booked a small row house unit G-20 from Aman developers, Dixit nagar, Nari road , Nagpur, Maharashtra. And given Rs 2 lakhs as booking amount through cheque dated: 19/12/2014. After few days it come to our knowledge from near-by neighbor that the construction quality of house is very poor and adjacent house wall fallen injuring one child. Their family also files a case against the builder. After hearing this we decided to cancel our booking. Builder asks us to make an affidavit for cancellation (for his accounting process). Same done and given to builder on 27/12/2014. From that day to till now. The builder is giving dates and excuse only, but not the refund money. Today they say we will only give money back once we find another buyer for the said property. My father in law is retired and he has given his retirement money for this property and presently staying in a rent apartment. He is losing time and his interest on amount. Please advice. We only want our money back with or without interest. Thanks and Best regards. Mr. Dhiraj Saijare Email: [deleted]