I had to HUACA twice earlier this week on an international SDC. I called because I already had an upgrade on the TATL flight that I was changing from and it looked like there was plenty of R space on the one I wanted to change to, but I couldn't tell from the website, so I needed the agent to check R space prior to doing the change.

The first agent did not have a clear idea of what SDC was, and did not know at all what R space was. So HUACA.

The second agent was much more clued in. She got as far as checking for space and then told me that there would be a change fee and an upfare, even thought there was space in the same fare class. She couldn't explain the latter, but insisted that 1ks did not get free SDC on international fares. So HUACA.

The third agent knew it all, but it took him 35 minutes to complete the transaction, including sending 8 identical emails to me.

All in all, this took an hour of my time, and UA's time. Multiply that by the number of SDC requests and the broken IT will cost UA lots of money, as well as ill will.