UKNZ: Thanks everyone this is really handy.
The main part of my case is that they are claiming damage to floors which looks like a couple of 1-3cm indentations in 5 rooms, very spread out and only 1 seems to break the surface and are claiming it needs a full sand and 3 coats of varnish in all the rooms, and they have 3 quotes for about $4k each to back it up. Seems insane to me, especially as the original floor looked patchy anyway. Cant they just patch the indentations?
(all of which is aside from the question of whether we actually caused them, but I'll leave that for now)
I think, they will have to be able to prove this is not normal wear and tear. So any photos you have of the floor while you were living there would be useful to you in establishing how the floor wore naturally.