W
White Room
The floor should be tiled first irrespective if UFH is fitted or not.
A pro tiler will only on a very rare occasion damage a floor tile when tiling the walls.
I cant believe you are having this trouble again with another tiler.
Even if they say they have 25 years experience then it counts for nothing if they have never tiled right in the 1st place.
I had a guy with 25year experience advising my friend that you PVA tiles before tiling on top of tiles!! :mad2:
I hope you get this situation sorted eventually.
If the tile joints are following floor to wall or has ufh laid then yes other than that walls first...IMO