If they can take money so easily why can't they credit it back? I'm sure musicians friend has the ability to just wire you the cost of the f--- up.
Credit card machines have the ability to work both ways, they can put money on your account just like they can take it off, but with the addition of a phone call and some authorization. It's just a matter of getting with a supervisor who knows how to do it and won't lie and say they can't.