What does your My48 account Dashboard say about your current membership plan status?
Is anything working?
Incoming/outgoing calls/texts and mobile data?
Maybe your membership plan has expired and you simply need to buy a new one?
What sort of message was it?
Email, text message, WhatsApp, etc.?
What exactly did it say?
If you need to contact 48 support about this then see the links in my signature below.
