How to get money back from builder?

Hello, I made a flat booking in june 2013 from one of the reputed broker firm in noida. Flat booked in ghaziabad with reputed builder (Wave Infratech). It was a prelaunch phase when i booked. Till date i have not got any official booking receipt from the builder. I paid 2.5L by demand draft against the 10% booking amount. Since then no further demand raised from builder. There is no construction at all even after 1 year. Every time i ask them, they give fake replies regarding construction. I am fed up by calling them for receipts of my booking but their representative keep on premising to send it within a weeks time. When i call back to check the status they say that the person you spoke with resigned and we will send it to you. However no such receipt sent till date. Today i spoke to one of their employee and he said it was the broker fault who submitted your booking form in feb/March 2014 ( i made my booking in June 2013). I asked that guy then how can you encash the DD which was on builders Name since it has a validity of 6 months time, he replied it was on prelauch and we encashed it without recording the original allotee name but only with broker name. I asked them to cancel my booking and refund my money. He said they will deduct 20-30% from the booking amount plus service tax and will return the remaining within 3 months time. How can they deduct money after so much harassment? Instead of giving interest on the money kept for an year, they told me that i will not even get the money i paid.. Is this justified? Can someone please help me to guide what should i do to atleast get my full money if not with interest. thanks Nitin nitinich at gmail dot com