Even if there is a problem on our end, all we'll do is waive our cancellation fee and offer a full refund. We're shipping out 3000+ orders a day--we offer the best customer service we can and if we've made an error we'll do everything we can to make it right. No one here works on commission and no one here will get in trouble because a cranky customer canceled on us.
Their next-favorite useless threat is "I'm going to dispute the charge on my credit card!" Go ahead. I've never once seen that work either, and if you do attempt it you'll waste your own time instead of mine.
Ask to speak to my supervisor? I love that part--it means you're almost done talking to me, and in an hour I can look at your order and enjoy reading over the list of empty threats you made before we canceled your order and blacklisted you.
My company doesn't ask me to take abuse from jerks, and for that reason I work a lot harder to satisfy the customers who ARE reasonable, even when they're justifiably upset.