Originally Posted by niji248

The world class Delta App is acting up so I called Diamond Medallion line to do a same day flight change. The agent told me that it can only be in the same fare category, so in my case I booked coach in X, upgraded to Comfort +, but willing to stay in coach for a later flight. The agent said no can do because there are no fare X seats available on any of the 12 Boston-LGA shuttle. I don't usually do SDC, but I've done it before on AA and never had any problems with either confirmed seat or stand by. Is it really the case with Delta or agent is BS-ing me?