Hi Mechman,
I've been having the same issue. Got my new 11 plate Bravo at the end of March and paired my iPhone 4 with no issues. It worked for a couple of weeks and then suddenly would not connect at all to the car (iOS 4.3 on iPhone 4 and software version 5.5 in car - it came with this installed already).
I then deleted users from the car and forgot the Blue & Me device in my phone. Once I paired the two together again, it worked, but when I tried to make or receive calls it would be exactly the same as you describe in your first post - lots of white noise and unusable.
I tried pairing my wife's phone (Samsung Wave) and it did the same thing, so it's not the phone. When I got home I disconnected the battery in the car for about 15 minutes and then tried pairing again (after removing users). It then worked as it should. Great, I thought.
However, it's not connecting again and after deleting users it will not pair at all now with any phone. The phone sees the Blue & Me system, but will not connect to it to allow pairing. So be warned, this may well happen to you. It may well be some issues with the new hardware in the Fiat range (all now have a unit that means you do not need the iPod USB adapter to play music).
I never had any issues with my phone on my last Bravo, so it would appear that the new system is problematic. I'm going to try to disconnect the car battery for about an hour tonight and check again, but I'm thinking that it's a trip to the dealership to get the unit replaced.
Anyone else with this issue?
What did you lot do to sort it for more than a week?