UA's call centers are incredibly inefficient at getting things done. For simple sales, I'm sure they're fine, but that's a function people would be better off doing online anyway. For making changes, even something as simple as getting assigned seating, they are either unable to do it, or it takes 4-5 times as long as someone who has a proper command of both english and UAs rules. I'm quite certain this largely elimates the cost advantage of the call center.
Honestly, I don't buy the "outsourcing is bad" argument. But it does piss me off as a customer when the outsourcing wastes a great deal of my time.