I have to say, my experience with bill collectors has been okay. And I’ve dealt with them both chasing after me and reaching me by mistake.
When i worked on a job where we answered each other’s phone i spoke to one who was trying to reach someone else and they were pretty discreet about the whole thing. I talked to another when I had a new phone number that had belonged to someone who owed money on a car. They were persistent when i told them they had the wrong person, but polite enough, and eventually left me alone. I’ve also had two bill collectors call me about money i actually owed, both for healthcare, and both late because health insurance bills are horrible. The first one managed to get the insurance company to pay, as they actually should have paid. He spent a lot of time chasing that down, and i was grateful. The second called me about money i owed. She was polite and persistent, but did get me appropriate documentation. I figured she was doing her job.