My problem is these people would never stop calling, ever. Like "The Terminator", it's what they do - it's all they do. The calling is automated so that a machine calls your number over and over and over (daily, not every five minutes) until it gets a live person. It can even discriminate whether it gets an answering machine or a live person.
I left a NASTY message on my machine until I figured out that it was being delivered to a machine. So you can not answer, but you still get five or six calls a day, all hang ups. I'm not a patient man - this tended to provoke me to violence, except the object of my rage is unavailable to express my unhappiness. That's when I started picking up the phone and telling them to leave me ALONE. That's worked fairly well, except that new charities still get my number and call, so I have to put a stop to them as well every now and then.
Worse still, you can get incessant calls if a debtor is the last person to have a phone number that was just assigned to you. For years our church used to get calls from debt collectors pursuing some woman, Vera something-or-other, alive or dead I have no idea.