More like out of curiosity: was it an OEM locking nut or some $2 Chinese stuff?

All OEM.

They said they wrecked their master locking nut as well - which left me with the issue that the remaining 3 bolts that I had put back hand tight, also could not be removed anymore ...

Sorry, I was thinking about my E53.

Ive been a bit confused by the term 'nut'

We are talking 'wheel lock', or 'wheel lock bolt', right? Just the standard, 'need a special key for the top of the bolt plus the 19mm socket to remove.

Anyway, in the USA you need to approve any work done on the car before they do the work. No so in the UK? Moot point after you pay it for sure....