Yeah, I had a flight go MX on me this month and went back to the TA who rebooked me in Y for my remaining segments. He said it was difficult to make changes to my itin because the medallion desk was trying to protect me at the same time. When I got home, I saw that the first segment was indeed in Y, but the second was in K which was the original fare. So, was the TA mistaken or did the medallion desk take another look and make a correction? I'll probably never know.