Norton subscription renewal

I just renewed my subscription when I still had 23 days left on my previous subscription. I now have 366 days left. Why did I lose the remaining 23 days? From my point of view my subscription should have either been adjusted to 389 days or my start time for the renewed subscription should have been internally preset to start at the end of my previous subscription! This situation makes me feel cheated out of what I paid for because that's exactly what I see has happened! Also, there are repeated prompts by Norton to renew NOW when the time to renew is within the last 30 days, so without some type of auto-adjustment to compensate for the earlier renewal Norton is purposely trying to cheat us. I'd certainly appreciate some type of explanation or solution to this problem.