Delay in Possession

Hello Sir, I have purchased a Duplex around 25 lac offer letter date 26/11/2010 thats having a clause " construction work will be started in phase manner and tentatively will be completed on or before 36 month , however if the completion is delayed due to any reason , such period shall deem to have been extended and second party shall not be entitled to get any compensation from us for such delay" and for delay in payment by buyer up to 90 days 18% interest if more than 90 days 24% will be charged i have paid 90% payment already they have changed some payment scheduled in offer letter and demanded increased payment on I,II, IIrd installment at present still we are waiting for possession and duplex in flooring stage they are delaying its possession date day by day. My Question 1) shall i file case in district consumer court for RENT amount we paid from Dec 2013 to till date, mental Harassment for living in rented house because of delay and interest on increased amount of installments as compare to original offer letter 2) Is there any remedy in New Real state bill for existing contracts 3) as per above mention clause our case is weak ? 4) what other compensation we can demand