So five months into this issue and a million phone calls later and just when I thought the problem was solved, it failed. I was so desperate for my handsfree in my car to work that I went into the apple store and they gave me a new Iphone 4s...
I get into my car (bearing in mind the phone at this point had none of my info) and it paired no problem. I then go home and connect it to my MacBook to install my info from Backup and the following day it won't work. So I get on the phone to Apple for the gazillionth time and they tell me it is probably one of the app's I installed, so I proceed to remove each one, I go to the Garage sit there with my phone and laptop and the light is green so it's nicely paired, I individually install each app (very very time consuming) I install all but Twitter and the green light in my car remains on. So I gather it was Twitter's fault and leave the app be.
I go back home and do not touch the phone, no new installations, nothing... the following day... it will not work yet again. So I've installed, uninstalled, restarted, restored, disconnected bluetooth, selected the "forget this device" on bluetooth, paired the device again, and nothing.
So basically, unless the phone has no information on it, it will not pair with my car or any other device for that matter. I can't believe I've been through all this trouble when my grotty old blackberry paired with no issues whatsoever. It's unreal to me that they can get away with leaving it like this!!!