So next service, I mentioned it and asked that the loose bolt be found, removed and, if it had fallen out of part of the door, replaced. No such thing happened.
A single bolt rattling around is of no real consequence and both Beloved Wife and I simply ignored the problem. However, over the last year or so the rattling got worse. I noticed it particularly after returning from a year in Qatar. According to Beloved Wife, the mechanics at Al Naboodah recognised that there was rattling as of loose mechanicals in the passenger side door, but either could not or would not do anything about it.
As I'm "resting between jobs" as out-of-work actors say, I currently have the time to deal with matters domestic. Beloved Wife insists that I'm not her house-elf.
I took the car door to bits this morning. As soon as I'd prised the inner skin away, three M6 bolts fell on to the ground. Further dismantling revealed that the dozen or so M6 bolts that are supposed to attach the frame holding the window motor to the door chassis were either missing, on the ground, or loose. I was able to retrieve all sorts of metal fastenings from inside the door, including all of the missing bolts.
I reattached the innards and tightened the bolts; something that a qualified VW mechanic had evidently failed to do. I also replaced the broken window winder switch, which was the original reason for pulling the door to bits.
And now everything works and nothing rattles. Why this relatively minor task was so impossible over at Dubai's Volkswagen agency remains a mystery.
And pleased with my success, I'm to spend this afternoon assembling Swedish furniture.