I had an issue with my Audi RS4 and 8120, but since it is a new car I took it in to the dealership and they fixed it. Took them 2 hours or so, I know it was not easy. I know Audi's have these issues (seems to be certain models only too) with certain phones and BT, but not sure about BMW. Try the dealership, even if the car is not new. Worst that will happen is they turn you away...