There ya go.
Seriously though, if they didn't take a picture, have it on video, or sign a waiver, it's always possible.
My friend's parents' van literally fell off a jack once. The repair shop tried to pass it off as "it must've come in this way" after trying to hammer out as many of the dents as they could. It took 6 months' worth of constant pressure for the stupid shop to cave in and do the work to avoid going to court.
LZ
Z