I usually hate calling customer service because I can never figure out which buttons to press or what to say to get a human on the line.
GetHuman solves that problem by listing the shortcuts for many different customer service help phone lines. I just tried it out for United Airlines (after getting fed up with the help website & the phone menu) and it absolutely worked! The secret: keep dialing 0 at each of the prompts. I was immediately connected with a customer service rep and had my problem solved in <1 minute.