mini cooper bluetooth issues

I have the new 4S iPhone and have for the most part been very happy with it. Recently my phone has stopped synching with my 2007 Mini Cooper. My old LG was fine and my 4S was working for a few days then stopped. I deleted 4S from my car and my car from the 4S. I then did a resynching process. THis worked for two weeks now it will not resynch regardless of what I do. Has anyone had a similar problem and how did they solve it.