I think I'm being scammed

glasgowdan

Don't pay. This is nothing to do with your neighbour or your surveyor. The roofer did work on your roof in error.

The fact that roof tiles/slates/ridges are so cheap leads me to think he'd leave it rather than go up again and replace them with old ones (he won't still have the ones he took from your roof). Though this assumes it's tile replacement that he did?

I wouldn't worry what the neighbour says - there isn't an issue until this roofer knocks your door and starts asking for money.

I'd also get up there on a ladder yourself and get some good photos from the ladder, see if there's any visible signs of repairs or any damage.