need advice

Hi All I had booked an flat in bangalore paying an booking amount of 1 lakh. Since the builder could not provide all the documents I had to cancel after 2 months.now the builder wants to deduct 14.5% of booking amount and return the rest. When asked he is saying that the Vat and service tax has already been paid and hence he is deducting. The apartment is still under construction and at plinth level. Please advise whether he has to pay tax for booking. Whatever he is doing is right? Need your experts advice. Regards Sunil Rai