Tried to use my UA miles to upgrade on a US Air codeshare flight from Charlotte to SFO. Grumply lady on the phone said I can't do that. When I asked what the Alliance partnership was about, she said something about it wasn't a full fare ticket. Ever hear of this? Went back and tried to find something on the website about this, but couldn't find anything other than a possible $25 copay. Did I miss something?