It was kind of eye-opening - they took phone calls form late-night tv infomercials and there was a script.
They would take down your name, take your order, and then... upsell, cross-sell, special offer sell, etc.
If the person said anything like "I'm not interested in this, blah blah", they had responses for everything. "But other people have quite upset when they didn't receive these very special offers and called back to complain"
It was carefully calculated. It was refined. It was polished and tested.
The only way OUT of the script was to say "I will cancel my order unless you stop"
If the call center operator didn't follow the script, they would be fired.
(You know this happens now with websites at scale. A/B test until the cancellation message is scary enough. A/B test until you give up on the privacy policy.)