Originally Posted by carofly

In theory you get a new date. However, it happened to me a few months ago, that I was just as the op at the last minute buying a cheap flight to get a new date for the rest of the credit. And guess what? The date didn't change.
I had been calling during that day the Spanish 800 number to ask about this voucher and to confirm that I would get a new date, to which the agents said I would. Well, when the date didn't change I called again in panic and was lucky enough to get one of the same agents I had spoken before. He was very understanding and voided everything in a matter of minutes.
Needless to say I had to book something for the entire amount of money.