I recommend doing a bit of research (in addition to ba.com, use the website of the airline you are hoping to fly) on your own before calling. I called last week and was amazed at how much more info the reps get in their search results, but I wouldn't have been able to take full advantage of this resource if I hadn't done my homework first. Interestingly, I was able to reconstruct the routing they found for me on my own (PVG-HKG-JFK), but had to do so segment by segment.