I've noticed a lot of games won't help in cases like this.
Basically, the stance is, you gave them permissions to take stuff out, it's your own doing.
Blizzard USED to have it so that you could set ranks to have to have an authenticator, so you could restrict withdrawals to those that had them, but you can't anymore for some dumb reason. I don't recommend letting people take that kind of money out of the bank.
I had it happen to my guild in EQ2 and I'd been the primary contributor of materials, spell books and platinum. It sucks. But I learned to not let people have those kinds of withdraw limits.
What would you expect them to do? That's my question. They're not just going to recreate the gil out of thin air.
