Help!!!Bank want more money! on line waiting.....

As in my previous email, bank accepted our offer. We signed back everything (offer, downpay proof, addendum)... listing agent said that we are binding into contract. then, listing agent said a few page need to correct (add title company in offer, split 50/50 for hoa and county tax which is paid by bank originally) and then seller will sign. Again, we signed the revised pages (all are prepared by listing agent). After this, we noticed that the property status is changed to pending. Now, listing agent said that bank wants to increase price (tens of K$), if not, they will not sell to us and property will back to market. Please help us for our options. Because the property is in pending state, and listing agent mention we are binding in contract in email, I already start looking for loans. Due to pre-approved letter we applying last year, now, our credit score is alreay in boundary which means if we don't buy this house, we have to pay at least a quater high interest laer or even can't get loan(below 700). So, we have damage if we quit now. Also, due to finacial situation, we can't add too much for this property. so, if we insist our price and bank doesn't sell us, who we can sue for damage? bank or listing agent or our own agent (I apply loan with her, and she has run our credit score already)? so sad and don't know what to do.....