Do not understand why I can't get higher speeds

I am told that the fastest I can get is 20Mbps. Yet the people kitty corner from me can get higher. I emailed Centurylink and they stated "We show fiber to the switch but not to your address". I thought to get 40Mbps was that you have newer copper and fiber to the DSLAM. I do have newer copper as my cul-de-sac was built in 2006.