I had a watch serviced by Rolex UK. (1990 Sub 14060)
They contacted me to say it needed a new crystal obviously wanting to confirm the extra expense. I don't remember there being anything wrong visibly wrong with the crystal. maybe internally it didn't seal or something. I aaccepted the extra.
It came back from service with the same dial but, I think, new hands. I don't think there was any lume working on the watch at all pre-service but now the hands shine like crazy in the dark and the dial is completely dark. They never asked about changing the hands. No idea why they did.
A year or two earlier I'd tried opening the case myself and made a real mess of the case back. It came back from this service with a new case back. They never contacted me to say they were going to change it and, as far as I know, they never billed me for the case back either. Maybe they somehow managed to polish out the scratch but it was really deep so I doubt it. Or maybe their final inspection guy wondered if they'd damaged it so decided to change it anyway.