What exactly do you mean by "SIM card invalid"?
Where exactly are you getting that message?
How many exactly is "a few months"?
After 6 months of not renewing membership 48 suspend the SIM/account and you have to content them to get it working again.
Could that have happened here?
When did the auto-renewal payment fail?
Can you buy a membership manually now?
If you need to contact 48 support about this then see the links in my signature below.
