Thanks for the update. I'm sure the dealer gets suitably compensated by BMW for sorting out warranty issues, judging by the hoops they've made my dealer jump through to sort out my various issues, but I'm also convinced that BMW have a system that encourages dealers to spend as little time on warranty issues as possible.
I was expecting to pick my own car up from its third visit for its various warranty repairs (including the roof problem) today as it's been in since Monday, but my dealer has also decided to keep it in over the weekend to be certain that the repairs have been effective. It's the first time they've done that, but I'm a bit disappointed as I don't even have a courtesy car. Oh well, maybe it's a good sign they need it a bit longer.
Still no info on the detail of the repairs, but I have asked for a full report for when I collect the car early next week. This won't give me much time to test it though - my car will be 6 months old this coming Thursday. I guess I can probably say goodbye to my full refund - not that I really want it, I just want a car that works reliably, but part of me is wondering, "Once a lemon, always a lemon?"
One thing is absolutely certain - I won't be keeping the car past the expiration of its warranty!