Because they hold the power over the phone. Yelling at a collection agent may just make them flag you as aggressive and who knows what they can do with the powers they have over my profile.
If I call a creditor, it is ONLY to tell them what I need them to do and what I want them to say in writing after they do it. I never negotiate over the phone, I never raise my voice, I never make threats.
When I had to deal with a well known horrible collection agency years ago, I answered their phone call, told them I have no knowledge of the debt they're calling about but since it was only $800 I'd be willing to consider paying it in full if they would put in writing what the terms of the payoff would be.
They wrote me a letter saying they would note the account as paid in full, so I called them back, acted very nice and said I would pay it the day I receive a letter saying they would delete the entire tradeline AND agree not to resell it AND agree to no more collection activities if I paid them $400 within 2 weeks of receiving the letter.
They sent that latter, I paid them, collection was deleted a few weeks later as agreed to.
Wasn't that difficult. They don't care about you, they want your money in the easiest and least stressful way possible.
If you can't keep your cool, don't use the phone. Tell them to do it in writing instead.
