Steven_L,
Thanks for your reply.
We have anothew virgin SIM, which when put in any one of three handets we have works absolutely fine. If I put the SIM with the troublesome number in any of the tree handsets they all have the problem. I have been sent a new SIM, this exibits exactly the same faults, again regardless of the handset.
These activities clearly eliminate a problem with the handset or the SIM, leaving only the network or the way the network is set up.
I note other people talking about disabling wifi calling, given the above activities, eliminating the handset and the SIM that this is a red herring. None of the handsets we have appear to have wifi calling as an option.
The problems statred occuring before the new SIM, on occarions the phone would display EE as the operator and prevent me access to mobile data unless I turned roaming on.
This has been ongoing now for approximately 6 weeks