It's outrageous that you can't cancel online as easily as you signed up, and we do need legislation to correct that. But when you have to talk to them on the phone, just say, "I sold the car." End of conversation. What are you telling them that gives them the hook needed for a 30-40 minute conversation?

If all else fails, "I was just diagnosed with a terminal illness" or "I am required to report to the state penitentiary on Monday" will work.