Why isn't a CC one year membership good for a whole year? Why has it died after only a few months?

You have not provided any system information or other technical details, so we can't know anything. Update failures have nothing to do with your subscription status they just are what they are - technical issues on your system. If the sign in doesn't work, refer to this:

Sign in, activation, or connection errors | CS5.5 and later

Mylenium