Further to my earlier post I have, at last, achieved solutions to the problems indicated. It has been a long hard slog but everything is now working as it should. The stupid thing is that once you have negotiated the wading through treacle aspect of TomTom support the resolution of the problems appears to be quite simple and straightforward; but they have to be carried out by TomTom personnel, things like resetting your sim card on the TomTom servers and so on (I don't profess to understand all that went on).
So although TomTom have been rightly condemned around the world for their inefficiencies; in fairness I must say that now (fingers crossed) I have a device which may just turn out to be brilliant.