Just today I was using the online change flights feature and when I had entered my CC number to pay the fare difference I hit submit and received an error. The error message advised me to hit 'back' and try again, so I did and simply entered into a repeating loop of errors.

I logged out of the site and back in, and lo and behold, I have no itineraries, new or old, and a search for my confirmation number brought up nothing so I had to call DL reservations to get the changes made...and even then they booked me on the wrong day but thankfully I got the email itinerary before I got off the line so I was able to have them make that change.

Oy!