I was just on the phone with Discover card customer service. (Yes, JMK, the same company that advertises "zero liability protection".) I was charged twice at a Chevron station when I filled my car with gas. I found it interesting that they can take care of most incorrect charges over the phone, but errors with the airlines must be dealt with in writing.
I also am learning that you must use short sentences, because they jump in whether you've finished speaking or not. Also, do NOT attempt to make two points at one time. Break everything down into simple issues. And, as soon as you pause for breath (and even if you don't), they will immediately give you their pitch. Instead of so much sales pitch, don't you think customers would appreciate being listened to better? But I am just one of those old fuddy-duddies who likes courtesy. I am soooo out of step with today's world!!