I've been having the same problem with my BT unit. I took it to the dealer, and they "reset" the BT unit, after which I could re-pair the phone.

About a week later, it happened again. I called them and asked how to reset, because I didn't want to come in again just for that. You unplug the power cable to the BT unit for about 30 minutes to reset it.

For me, that didn't work the next time, so I am taking it in to get the unit replaced, when I can make some time to do it.