Twitter works really well. You will still be dealing with a bot in the first round, but if you have a narrowly-defined problem and you make a narrowly-defined request, it is useful. I believe that if you don't get anywhere and respond, it makes its way to a human.
E.g., "I was charged $2 extra in wait time because the pickup time was incorrect. It reads 13:11 and was really 13:20. Please refund the $2"