Motorola M8989 in-car phone - stopped working

[mousemat]

Can anyone please, please give me some help with the Motorola M8989 (I think that's the model number, now discontinued) phone fitted to my X reg Jaguar XK8. It was working perfectly (I recently bought the car) and now it's not! There is power to it and it comes on as soon as I turn on the ignition but although it accepts the PIN, after some searching, SIM1 messages, Jaguar logo and blank screens the phone asks for the PIN again. I have tried various things like reseating the SIM, phoning Orange (who said it wasn't a SIM problem) and Motorola (who said it was a SIM problem!), spoken to my Jaguar main dealer who say they can't help, etc. If it had never worked I could understand it but it was fine for 2/3 weeks........Very frustrating!