I think that Microsoft should send out a courtesy email prior to charging your card for another year. I hadn't been on XBox Live for about 6 months and didn't know exactly when my year was going to expire. Luckily the CC that I gave them expired last year and they couldn't charge it again. They sent me an email telling me that my CC was expired and I needed to give them a new one or my account would be suspended. I guess my account is now suspended.
I don't like the fact that you have to call them to cancel your account. You should be able to cancel online.