Another frustrating EUA experience in the making...
I'm flying "direct" from PHX to LGA today with a stop in IAH (same flight number, less OnePass miles, and fewer segments...) and the IAH-LGA segment is oversold (A6 D4 F0) but the PHX-IAH segment has F seats available (A6 D4 F4). My upgrade didn't process because "the whole flight has to clear on a direct flight or nothing clears"

I inquired as to why, but was blown off and told that it would "inconvience me" if I was in F for the first segment and coach the rest of the way...I eventually got the agent to explain that the computer doesn't allow for those segments to be separated and therefore couldn't process the flight partially in F and partially in Y--with the hope of getting the rest of the upgrade later.

She tried to manually separate the flight into two segments, but the computer wouldn't let her resell the connection with the same flight number.

Why has CO taken all power away from its agents (including this supposed supervisor) and given it to a computer that is missing a few lines from having the program correct?