I've used them before....very convenient. I tried to buy some on 9/1 in termimal C, and the transaction never went through - said something along the lines of "unable to communicate with center" or something. I never got the coupons, but CO put the charge for $13 on my Visa debit though. I called CO to see what to do, and after about 4 transfers, and 20 minutes of holding, I just called visa, and they deducted it immediately. Nobody on CO seemed to know how to handle the situation. One agent didn't even know what "Continental Currency" was. Anyhow, it worked out. Hope that doesn't happen again when I try to buy them.