Provident Rays Of Dawn (Mysore Road) — not ready to refund the booking amount after cancellation.

Hi all,
We have booked a flat in provident rays of dawn in mysore road, bangalore just a week ago and want to cancel the booking due to some personal reasons. Paid an amount of rs 1lakh towards booking which the builder is refusing to return saying that for cancellation they take 15% of the total flat cost. Can someone please guide us with a good lawyer to file a case against the builder or to do the needful.

Regards
Sitha