As per another thread I have been unhappy with the Bluetooth and the echo/feedback issues. I note some other folks have also had similar issues...

Well today I was flipping thru the little guide in the glove box and on page 6 there's a "little" clue that made me think

The volume can be adjusted independantly via the radio volume controls OR your mobile phone
I first checked my phome volume while not connected and it was on 10, connecting to the car kit it was now 1.

Seems each paired device has it's own profile inc the default volume.

I went for a drive and called the missus and played with the phone volume and the car radio volume while chatting.

The echo is now all gone.

My phone is a Nokia 6233 and I settled for having the phone audio at 10 (max) and that meant the in car violume was considerably lower.

Now I can have the fader and balance set at neutral with no echo or feedback even when I talk over the other party which was a sure way to cause echo before.

Hope it helps.