I once had an auto mechanic key in $22,000 (accidentally) for a $2,200 repair on my Chase Marriott card days before a 2 week vacation which pretty much wiped out the remaining credit. I was more concerned about not being able to use the card for the points. Called Chase and they really could not have cared less about the timing, it had to run through their normal processes and no one is concerned with the speed when it comes to returning money...