My phone will not allow me to use data roaming despite my carrier confirming it is functioning ok,

My phone will not allow me to use data roaming despite my carrier confirming it is functioning ok.

I have tried:

• turning phone off & on again
• turned data off & on again
• switched data between 5G only, 5G auto, 4G
• checked with network provider who confirmed who confirmed I should have mobile coverage

i have an iPhone 13 pro

at this moment in time, my iPhone 6 was more useful when travelling:

help appreciated.

Chrissie