TP2 Mercedes Bluetooth Issue

Hi all. I've been a member on here for a few years but never posted as I have always managed to find the answer I was looking for by using the search function. This time however my search engine fu has failed me!

I have a HTC TP2 running WM6.5 which worked fine with the Parrot hands free in my VW, but I have now replaced the Dub with a C class Mercedes and the phone refuses to pair with the factory fit bluetooth.
I am able to pair my Blackberry Curve without issue and likewise a Nokia E50 and Nokia 6300. When I try to connect the TP2 I enter the passcode into the car and the cars bluetooth comes back with "error unable to connect." No other hints or info.

Searching the Internet revealed a guy with a similar problem who said the users on this forum guided him through updating a cab file which solved the issue, unfortunately he didn't give any more info or a link to the thread. I have also seen posts suggesting an update of the bluetooth puck may help.

Any hints tips or suggestions would be hugely appreciated.
Many thanks in advance, Pete.