Alhambra Palace tickets (Granada, Spain)

You can just show your old card. Often people pick up their tickets in town beforehand at a Caixa machine. Even though you need to insert the card used for purchase, it all works out.
By the way, I understand Ticketmaster voucher still talks about entering in morning or afternoon time slots. Disregard that. If you don't know already, there is no longer entry restrictions to the grounds. You can enter anytime. Only controlled time sensitive is the entry time to Nasrid palace.

Thank you Maria.

I'm glad that it'll all work out after all. Thanks for the access tip as well.

We picked up our tickets at the Coral de Carbon, which has two ATM like machine which prints out the tickets. Even if your old card is blocked, you will need to carry that old plastic and use it in the machine.

New Question: We plan on purchasing our tour of Alhambra tickets as soon as they become available online for our time frame; April/18. It states that you still have to line up to collect your tickets; do they have a separate line for ticket holders?
Thanks,
Jean

Jean, you have the option to pick them up beforehand - unless you are buying specially priced tickets (like senior's tickets). If senior's tickets, there is a separate line for it. Some have said the 5E savings wasn't worth having to go all the way up to the ticket booth as it is a 15 minute walk down to the Nasrid Palace entry. Some say if they had known, they would have just paid for a normal ticket, picked it up at Corral de Carbon office or the Caixa bank machine and entered through the Justice Gate which is very close to Nasrid Palace entrance. Hope that helps.