U.S. Hardback edition, Prisoner of Azkaban, chapter 22 ("Owl Post Again"), page 433. "Crookshanks took the order to the Owl Office for me. I used your name but told them to take the gold from my own Gringotts vault."

I have a strange feeling Crookshanks is an Animagus. I mean, a cat doing banking? I wonder if Crooky can balance my checkbook :P