What exactly is not working?
Calls? Texts? Data? All of these?
Did they ever work?
What does your My48 account Dashboard say about your membership status?
What does your Transactions page say about recent payments?
Did you enable roaming/data roaming and configure your APN settings?
If you do a manual search for networks can you see and connect to 48?
If you need to contact 48 support about this then see the link in my signature below or email them at email@example.com