As above, they should of got a signature and pics of the damage before leaving site.
But Just for a funny story I was involved with some MEWP damage once, Allbeit not directly.
Me and a coleague were doing some work on the outside of a building with a 90ft Cherry picker, One of the big 4x4 all terrain ones.
Anyways we had alot of rain and the ground was soft so we were a little aprehensive over driving it on the grass.
We were told it would be ok so went for it.
I was playing banksman, Got half way accross the grass all going well when we hit a really soft bit and the one tyre sank pretty much instantly!
Well to cut a long (but amusing) story short it ended up stuck and sank right down the to axel, The biggest issue was the wheel the other side was on a concrete pad so the whole lifter went on a angle, Bent the axel and knackered up the wheel amongst other things.
Wish I still had the pics as it was a sight to behold I tell ya!
Cant remember how much the repair bill was either but it was pretty damn expensive!
