Regarding flat cancellation and refund

Hi, I have booked a flat in Hyderabad on 7 june 2015 by giving 20% amount and went for home loan for remaining 80% amount. As the builder project was already sanctioned from OBC bank so i also go with the same bank for home loan. Whey i applied for a home loan bank again did second legalization of the land and project and they found some issue in it. ( as per bank there are some owners names are missing ) so they have denied giving home loan to me. I got in written from bank due to what reasons loan can not be given. Now i dont want any future risk so want to cancel the flat ( till now i have given 20% amount which is around 6.5lac ) and as per sale agreement 1) in case of cancellation 10% money will be deducted from total amount given till date. 2) refund will be given only after once project is completed or same unit is sold to any other customer whichever is earlier. Now my problem is how should i approach to get my refund because as per agreement it is not possible because no one will buy a flat if there is some land dispute.