I wrote an email and faxed a completed "Expired Gift Card Extension Request" to Epay NZ Ltd, who run Gift Station. They deliberated for a month or so and sent me an email extending or a further 30 days.
use cards as soon as possible to receiving
don't save for a rainy day
gift cards from different places have different length lives - check each one.
It always pays to ask. I was very pleased with Gift Station's service.