A discount you can't use isn't compensation

When something goes wrong, companies love to offer a voucher or a percentage-off-your-next-purchase as compensation, rather than money. One family was given 25% off future flights by SAA. Generous, until they tried to book and found there was simply no way to apply the discount at the payment stage because their foreign credit card wasn’t accepted. Before you accept a voucher as compensation, ask: how exactly do I redeem this, does it work on the fares I actually book, when does it expire, and can I use it online or must I call to make the booking? And make sure you get the answers in writing.