Buying Flat from Landowner Allocation

I have booked a flat from a reputed builder at Kolkata which is from the Landowner Allocation. When I have applied for Home Loan, bank said that they can only disburse the amount in the landowner's account. But the builder wants the money in their account. Hence the Bank had requested for the following documents which the builder is taking time to give. 1) Sale Agreement between Landowner & Builder(In this case wife of the Director). 2)Registered Power of Attorney given by the landowner to the builder. 3) Landowner to sign personally and third party will join as confirming party in Nomination agreement & Reg. Sale Deed favoring buyer. Builder has communicated they would provide the above documents(1 & 2 mentioned above),but the landowner would not sign in the Sale Agreement nor in the Sale deed, only the builder would sign(As stated in Power of Attorney) on the landowner's behalf in both the documents. I have already paid my share to the builder in their account. Please suggest whether I would go ahead with this deal or back out or any risk is associated if any heir of the landowner claim their share in future. Also would like to know if the builder would return back the whole money which I have paid to them in case they are not able to provide the sufficient documents required by the Bank.