Keeps calling and hanging up

I have received several phone calls from this landline phone number at all hours of the night and day, sometimes its a female and others its a male. They once claimed to be with a magazine subscription something or other looking for someone named Blu. I informed them that they had the wrong number and to please add me to their do not call list. The next couple of times i requested to speak with their supervisor only to have them hang up on me. They continue to call my phone and just hang up with either a sarcastic, foul remark/comment or with n words at all. This is harassment and I would appreciate any assistance or help in dealing with this annoyance, thank you.