Money paid into wrong bank account

I'm very disappointed with the service I receive from them. I receive money that I should've pay to the doctor, but they transferred it to an old bank account. The minute I received notification (they send us an email before payment are made) that the money will be paid into the wrong bank account, I notified them. But according to them they can't stop the payment (the money was transferred 2 day later), apparently 2 day were to short notice. The money is gone.....even the bank told me that it sound very strange to them