One day last year I routinely checked the oil on my Arosa and realised that the plastic oil filler extension pipe on top of the rocker cover had started to distinegrate as it's mainly plastic - I fished one large piece of plastic out through the hole but thought I'd better go straight to a dealer to have them remove the rocker cover in case there was anything else rattling about in there waiting to get sucked into the injectors. I probably could have done this myself but I didn't know the torque settings for the rocker cover bolts and I didn't have a replacement gasket handy, plus I was afraid that debris would get entangled in the motion at any moment.
To be fair, Arnold Clarke accepted my car at zero notice at a time when they were clearly very busy - I went for a walk and came back three hours later to be told that no contaminants had been found, and was charged ~ 40 pounds which I thought was reasonable for peace of mind.
I then drove about 70 miles to my next destination and lifted the bonnet to refill the screenwash only to find that two pipes normally anchored by tabs slid under the front rocker cover bolts were dangling loose - they had forgotten to put these back in place when they replaced the bolts. So of course I ended up loosening the bolts, refitting the pipes and retightening the bolts myself to what seemed like a 'reasonable level' of tightness, exactly what I had tried to avoid in the first place.
Parts - good and bad experiences there too - went in with the aforementioned oil filler extension pipe and the guy sitting in front of the computer insisted that the part I had in my hand was not available for my car, referenced by registration number - even though the part I had in my hand had been on the car for the eight years that I had owned it. They duly ordered the part they thought it should be - I allowed them too, with reservations, thinking maybe the original design had been modified to make it less liable to fall apart. When it arrived, it was completely wrong. I only got the right part when I insisted they order the part I had in my hand, using the number stamped on it, and disregarding any other details.
By contrast, I went in there another time to enquire about the cost of replacement door handles / door cards (I wanted them in black - the originals are light grey, nearly impossible to keep clean). A different guy (younger) patiently went through everything finding the prices for me, only for me to decide that I could not justify ordering them as they were so scandalously expensive - he'd been so helpful that I felt I had to apologise for not ordering them in the end.
The other
problem is that the parts bit is in an anonymous industrial unit some distance away from the main premises - remarkably hard to find if you've never been there.