If you were to call me up and start yelling and screaming, I would probably just quote some policy at you and hang up. If the place agrees, you get your money back. They have no personal investment in you or your problem, and the bigger a jerk you are, the less likely they are to want to help you. And the best way to deal with this is to do everything you can by looking at the last two words in your post. All you can do is patiently explain why they are wrong and if they persist, ask them to leave, or hang up.
It is similar to our craze with diamonds, planted in our societal subconcious by a cynical marketer.
Will this satisfy all the crazies who just wanna get mad? The couple next to me in the place were pissed because their ribs took more than 24 minutes to be prepared and delivered. Being that they take more time, drive away other legitimate business, reduce morale, etc. I understand that telemarketers are just trying to earn a living and get through their day. You will find people much more helpful when you treat them like another person.