<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by AAlton:
Specifically, I paid for a generic fare in L inventory sometime ago for a friend to visit meet up with me during her spring break. I purchased it well in advance, not to lock in the fare, but because L availability tends to vanish quickly over spring break. Now I find that there is a sale fare in L quite a bit lower than the price I paid. I called American Airlines, requested a rollover into the sale fare and they happily exchanged the original ticket for another ticket at the sale fare. The difference was refunded back to my charge card.</font>
Usually airlines will issue a voucher for the price difference without charge, at least AS, DL, and UA do. The fare class has to be available on the your flights to qualify. Sometimes there are restrictions such as webfares that don't qualify. If you actually want a refund to your credit card you may have to pay the applicable change fee.