If the Seller's don't have any money (which is likely the case in a short sale) they can't pay. If the bank won't pay, then the sale will not go through. The agent can ask the bank, and if they refuse then the only options to pay it are you and/or each agent. Sometimes it can be split 3 ways between the buyer and each agent. The agents are resonsible because they had you sign something that wasn't accurate.