Sean444
48 is A MVNO (mobile virtual network operator)
Although a separate company, it uses 02's Network...you could say 48 are roaming on 02 Irl.
Data roaming should also be present on your signal bars area of your screen.
Leave data roaming constantly on, as in most cases, it's needed to pick up signal, and at no cost, I assure you.
The settings should be fine when, as mentioned - you should have operation when you toggle data roaming on.
If however you do not have operation, post back your make/model of handset and account status.
🙂