Builder forcefully asking to go through a specific bank for loan

Hi, I purchase a flat in Pune, before registration builder said that each and every thing is clear but after registration, we got search report in that they found some problems. 1. They don't have an NA certificate of 1 building out of 10 building. 2. The project plan is approved but having a clause -they must have Environment certificate. but now builder saying that they will not get Environment certificate because they don't need but banks said that if it is clause we want it. builder increases pressure on us to take loan from PNB or HDFC only two banks given approval. The builder said that if we want to cancel a flat they will refund money, but will not refund stamp duty and registration. we are not sure what to do.