Unethical Builder - VISHWA Associates Developers Promoters and Builders Pune

We booked flat in Feb 2007 with Mr Kusalkar of VISHWA Associates Developers Promoters and Builders. Rate agreed was Rs 1950 per Sqft and later as market rate increased Builder demanded higher rate and later when I went onsite he sent legal notice saying rate agreed was of Rs 2750 per Sqft and as I could not deposit remaining money he is canceling my claim on said flat. Only Mistake is I made was trusted this builder and gave him cash for stamp duty registration and other charges which he said will be paid back only if I sign cancellation form as per his conditions and I had no choice or loose entire money given to him. I just want to bring to notice of all about this builder beware and don’t deal with this company as their other properties are under litigations. Hope this helps.