What worked for me was being able to recreate the noise. If I could not predictably recreate the noise it was useless as they would come back with no problems found.

My multicontour seat back squeaked horribly and all you had to do was put pressure on the seat back and it happened. They fixed that one on the first try by taking it apart and putting their "anti-squeek tape" on the problem spot.

My X5 had a little over 31K miles and I finally got BMWNA to buy it back due to all of the rattles and noises. I think it helped that the dealer took the dash out 3 times and they never could get the dash level after putting it back together. The dealer had the car for over 6 weeks and even though BMWNA said my car didn't qualify they bought it back as a courtesy.

I'll say that BMWNA was very good to me and I will probably end up with another BMW at some point.