I keep getting calls too, daily from a Keenesburg, CO number. I've requested they put me on the Do Not Call List multiple times. Not sure what to do next.
If you are on an iphone, add the number to your phone as SPAM. Then at the bottom of the contact, there is a button "Block This Caller". I have all of the SPAM numbers in there that I have ever gotten calls from. The list is really growing, but at least I no longer get repeat calls from some of these people! I am sure an android phone has the same feature, but I don't know specifics. Hope this helps!