UPDATE - Basically I thought I'd try using the OBD scanner I bought, this was a CARISTA branded one with an app on iOS or android, not long after I plugged this in and started scanning the ECUs (sorry if that's the incorrect terminology) the bluetooth module magically came back into existence - HURRAH...

Alas, it was to be short lived as whilst I took the car out for a road test with Bluetooth tunes yesterday and all was good, today it is now not working again, ...

I can only surmise electronic gremlins and I can't see a way to fix it without getting an in car electrics specialist at this point, seems a bit impracticable to plug the OBD scanner in every time to kick start the combox.

If anyone has any more ideas I'd be more than happy to here them!

On the plus side, this means the combox is not a complete dud (I think).

Thanks, Nick