Sounds like a question for the State Attorney in your state.
Something is really off with that bank, Anon.
The bank doesn't get to tell you to renegotiate your contract with the seller.
The bank doesn't have that authority. The bank can only determine whether or not you get a loan from them at "x" amount.
The contract is between the buyer and seller only, contingent upon financing within a certain amount of time, (unles it's specifically written in the contract that way).
Try another bank.
Try 10 other banks.