Last night I was messing around in my guild when I noticed that if I relogged it continually reset the amount of gold and daily withdrawals I had to their original amount. I was able to continually remove gold and withdrawal limit after each relog cycle. You could tell your guild that you're having connection issues and wipe them out. This is on the US realms, looking for someone else to confirm for me.
Edit: Apparent repost, delete this if so. I couldn't find anything after searching for Guild Bank about this though.