Gilt City is a scam. You purchased a voucher there and only two things might happen: 1. The website is down and you cannot see your voucher. But they won't refund you because of the 'user agreement'
2. The vendor was not aware of the voucher.
Either case, don't count on the customer services because their average turn-around is > 1 month --> at least by then your voucher, if valid at all, would have already expired :)