I couldn't disagree with this more. It's not the calling themselves who is deciding to keep calling back, it's the calling system. Often these people are very young, physically disabled, immigrants to Canada. They have few options and not doing this work is not a realistic option to them. I've also worked as supervisor at a call centre.
When I worked at a call centre at 18, I was forced to call back "refusals" meaning people who asked us not to call back. This was humiliating, degrading, and something I was strongly against. However, if I were to just leave, refuse, or quit, I wouldn't have been able to afford to eat. To say I deserved it when people were nasty to me is downright insensitive.
I don't believe in judging people, especially without any information. To say you can somehow judge a human being from a 15 second phone call or two, and say they are deserving to nastyness or cruelty is completely unacceptable in my mind. I know what it's liked to be judged as a sex worker, and I try not to do it to others.