Bluetooth connection to Audi A4 still drops after 2 months of trying everyt

I have a 2007 Audi A4 and paired my iPhone to it. The Phonebook transfered over and it works for the most part. However 9 times out of 10 the Bluetooth connection drops about 5 minutes into driving. It then picks up the connection a minute or so later. I do have it connected to a charger (which reduced the problem a bit).

I really don't want to buy a Bluetooth headset since I already have what is a perfectly working (and expensive) car system that paired fine with 2 other phones (Sony Ericsson T616, Motorola SLVR).

I'm becoming increasing frustrated, especially after a near accident when I had to pick up the handset and lower the stereo during a recent dropped Bluetooth connection.

The iPhone is brilliant, but this dangerous glitch is a deal breaker for me. I'm now seriously considering a Blackberry instead.

I tried everything over the past 2+ months including:

- Bought and used 2 different iPhone car adapters
- Installed all iPhone updates
- Turned off auto locking
- Kept the iPhone on the Phone screens (Contacts, Recents, etc.)
- Turned off WiFi
- Disabled Bluetooth until just before pairing
- Restarted my iPhone prior to pairing
- Restored my iPhone prior to pairing
- Factory reset prior to pairing

Interestingly the pairing worked for the first day after each of the past 2 iPhone updates, but the problem came back on day 2. That's why I performed restores and resets (which didn't work).

Any thoughts?