Been getting calls everyday like above. No message no clue.

I do not know who these people are and they won't leave a message. They also use the phone numbers: 303-578-1005 and 303-578-1010. I usually don't answer unknown numbers, but I finally broke down and answered because I was at my wits end. Each time I answered, they would ask for someone I don't even know. I have told them that they have the wrong number and to stop calling me. On two occasions they said they would, with one person going as far to tell me that "I'm deleting your number from our list right now" (obviously she didn't). The last time that I asked them to remove my number, they just hung up on me. They are now on my block list and when they call they go directly into that lovely black hole, but I'm still annoyed that they keep calling, usually 4-5 times EVERY DAY. I have filed multiple complaints with the Do Not Call Registry, but I haven't seen any change. In fact, the frequency of phone calls seemed to increase once I filed my first complaint.