Lost mobile data - Can make calls but only get data on wifi - "3G" displayed - 4G calling = "Not Registered" and flashing

Thank you.

Lots to cover here, i’ll update you on what I have tried:

“To be sure try rebooting after changing to ‘Dual’. I forgot to mention that.”
Fear not, i was doing that.

“You said it worked on your XA2. So try the settings you used there.”
The settings were quite different on my XA2 Plus, and i did faithfully re-enter them into the 10 iii (see attached).
Still didn’t work after a device restart.

One thing that is different between the two phones is the “4G Calling feature”, which I had mentioned was blinking on and off. I did manage to get it to search for networks, find talkmobile, and when i came back it had stopped blinked, and was set to greyed out.
Still didn’t work after a device restart.

One thing I should note, is that when I first booted the phone (and again when sim swapping just now), I got a text from talkmobile promising a text that would contain further settings.
Neither of these texts ever arrived.

I haven’t yet managed to try the developer mode stuff.
Is there anything in what I have told you so far that provides further clues as to the cause?

Thank you again.

20220723_185127
20220723_185117
20220723_185051