Last night I noticed that if I flew one day later on a TATL flight I could secure space in B/F using a GPU (R space was available). I called UA, gave them the routing, and was told that not only was that seat available, a better, non-stop flight also had R availability. I took the better flight, but the agent needed to call the rate desk, and the entire transaction took about 30 minutes before the ticket could get issued. As the title suggests, the R inventory on all the flights disappeared, and the agent refused to refund my $400 change fee, but offered to move me back to my original routing, for an additional $400. In the dim reaches of my mind I recall an agent once "grabbing" the R fare before making the change, so I wonder if this agent just didn't know enough to do that before making the change. In any case, it seems to me that I should at least get my $400 back, or get sent back to my original routing, with no change fee. Feedback?