They'll probably just say "oh man, so sorry... wish we could help but...". I had tickets for Fall Out Boy (yeah, yeah) the second they went on sale last month, and their server crapped out during the credit card authorization. Unfortunately, it hung there for 2 minutes before booting me back to the homepage and saying "your order may have gone through, if you don't receive a confirmation email in the next 15 minutes, try again", like that would do me any good.
I called them up to see if maybe they had some record of my attempt, but of course... no dice, and since the concert sold out within 5 minutes, I was SOL.