Twice this has happened to me. I've canceled a ticket (after 24 hours). I went to book another ticket, and the price difference was $20. Okay, so I pay the $100 change fee, and I am supposed to receive a $20 travel cert. right? Yes. But, I never receive one in e-mail. I do this a second time a couple of days ago, except for a $30 difference between the fares. Again, no e-mail with the travel cert. #. Has this happened to anyone else?