When was it working ok last?
What changed in the meantime?
E.g. phone software update, settings changes, factory reset/restore, new phone handset, returned from roaming abroad, etc.?
What happens if you do a manual search for networks?
Can you see and connect to 48?
Can you try your SIM in another unlocked phone to see if it works there?
If you need to contact 48 support about this then see the links in my signature below.
