Am I eligible to file a case against my builder ?

Dear Advocates, Please help me whether I am eligible to file a case against my builder. I bought an apartment with a reputed builder. I bought the flat in November 2014.The possession could have happened by August 2015 as per the agreement.The UDS registration and sale agreement registrations are done in Decemeber 2014 itself. In the agreement, the builder mentioned 3 months grace period after which he will pay 2rs /sqft (only super built up area). Now the builder says he will complete by March 2016.But if we look at the progress, there is not much done.But as per agreement, he already took about 90% of total cost of the building from us. Apart from this, the builder is doing the following: 1.Not providing windows as promised. 2.Some of the ameneties like Ratriculated gas connection is removed without any information to us.And there is a huge amount collected from us for that amenity.And if we ask now, the builder says the give us back only 10% of what we paid. 3.Construction quality is going bad. Very irresponsible builder, and no communication so far on what is happening and all.There is no hope that he can provide me the flat in next 6 months also. I am a middle class person and because this I am facing many difficulties. Could you please help me whether I can file a case against him and recover my money. What are the chances of winning this case .I have put my hardened money which I earned in many years, by looking at the current situation, I am really disappointed. Thanks in advance, knk