I know this isn't exactly the same situation, but my travel agent was unable to book various flights for me shown on ITA, LH.com, and other sites using UA. She said that they cannot construct anything these days, only take what the system gives them. I had already had her do a fair bit of looking so I felt like I didn't want to push the point but it was really frustrating. I understand this is CO's business decision but I don't like it (and I was actually trying to get a more expensive fare class in order to use upgrade instruments). Sounds like Kayak is the way to go--can they search for specific fare classes?