It depends if you registered with lifeline online before I'd imagine.
If you did then I guess your old username and password will become active. If not you'll need the pin number that goes with your card and your c should be able to give this to you.
I found exactly the same. I rejoined last wk, thought my old log in would work but it doesn't. I asked tonight and they gave me a pin to use, I'll try it at work tomorrow