[Resolved]  Siddhitech Homes Pvt Ltd — Builder demanding high maintainance and not giving possession date in writing

I have purchased a flat from Siddhitech builders and want to register the flat. The builder has given some clause in the agreement stating that the maintenance of the flat is 40 Rs per sq feet. The builder is continuously harassing the members by increasing the area of the flat and then demanding a very high maintenance. He says that he cannot give the possession date in writing. Because of this I cannot register the flat. Can someone tell me what can I do in such conditions.