What to do if construction work is not completed as promised?

We around 40 home buyers, who have gone into agreement with a Builder couple of years back.We have home loans from reputed banks like SBI, Corp bank and Andhra Bank. And the banks have disbursed from 50 to 90% of the flat cost, without proper verification. Some buyers have already registered also. But the builder was into some legal issues related to other projects, and went absconding in September last year. FIR lodged by all the buyers at a police station near the builder's corporate office. In last Dec, the builder introduced us with one of their investors, who was supposed to complete the project and hand over to us. It's already an year over but there is not much progress with respect to construction. Though the builder and the investor has entered into a partnership agreement, the buyers have not got any document. The banks were reluctant to disburse the rest amount. But any how the new builder(investor) has convinced them with NOC from buyers to accept him. Please suggest!