Builder is not returning booking amount on cancellation

Hello Sir, I booked a flat with Puravankara builders for their new project Purva Silversands, Pune during pre-launch phase in November'16 by paying a booking amount of 1lac. At that time sales person confirmed on mail that if I'll cancel my booking before 26th November then I'll get full refund. Then i sent a cancellation mail within that time period and visited their office to complete the cancellation process but they denied to pay booking amount and said that amount is forefieted and can't be refunded. they also showed me booking documents which i signed (not a legal one) stating that booking amount won't be refunded. and so I asked to change my unit and asked for extension to pay amount for registration. they granted an extension till April'17. Now due to financial problems i am not in a condition to pay registration amount and requested them to cancel my booking and refund my money. But they are saying that you won't get any refund as so much time has been passed and amount will be forefiethed. till now i haven't signed any legal contract or registered my flat. is there any way to get my booking amount back?