On a direct Ted flight from IAD-LAS, the video equipment was not working for the entire plane. The flight attendants never announced the issue to the passengers, and for the most part, no one seemed to notice. Courtesy of valuable information from FlyerTalk threads, I submitted a complaint via united.com. After roughly 4-5 business days, I received an apology e-mail from a CSR, and about 5-7 business days after that, I received a $150 discount travel certificate in the mail. Needless to say, I was pleasantly surprised.
I also had an eerily similar experience during a direct flight from IAD-DEN. The audio jack was broken for my seat, and when I e-mailed united.com, I received another $150 discount travel certificate in the mail about 2 weeks later.
While my experiences might be exceptions to the general rule with United CS, I encourage you to at least e-mail them directly. If I received $150 for a domestic flight, it’s certainly possible you could (and in my opinion, should) receive more for an international flight.