I have a 2005 X5 4.4 and have had very little problems with the car.

I agree with the suggestion of trying another dealer. Or maybe you should call the service manager at the current dealer and discuss the problem with him.

The problem you are having while aggravating will not leave you stranded.

I had a Volvo with a check engine issue that caused me to visit the dealer many times. I that case the dealer worked hard to solve it but it talk many tries. Today's cars re lie on computers and it is hard to solve an intermittent problem.