Flat booking

Hi.all.. I've booked a flat in Kharagpur of west bengal, which is under construction and the agreement is also made on 07/06/2013. It has clearly mentioned in the agreement that fully constructed flat will be handed over to purchase i.e. to me within 24 months. But the builder didn't hand over the possession of the flat as the construction is not yet completed. It will take 6-8 months more time to get the flat constructed. I have already paid the necessary amount (14,50,000/-)as per the construction development. I've taken the home loan from IDBI bank and paying the interest every month. I'm getting monetary loss for the time has been lapsing. The builder/promoter is not taking any initiatives for Speedy disposal and not attending my phone calls. Hence, I requested you to give me the legal suggestions for better approach into getting back the monetary loss and get the possession of the flat soon.. An early reply is highly solicited please.. Thanq.. G.S.Rao.