回复：紧急询问，第一次买房，3月份看上了一个新房

you may "try" discuss with the agent for returning portion of the commission before you sign the contract. But the agent may refuse to do so as well, because he/she deserve the money.

Too late now, it's not easy to back out unless you really can't get the loan. Your mortgage will do their best to sell you the mortgage. Even if you can't get the loan, the seller's lawyer will request you to try next mortgage company. I think you will need to show them that you have tried 3 mortgage companies.

However, you should be very careful about your next step, otherwise you may lose your deposit.