Because payment is sent directly to your attached payment account (Stripe and/or PayPal) you need to issue a refund (in part or in full) in that system and void the gift card in Gift Up!
1. Log in to your Gift Up! dashboard
2. Find the gift card you would like to refund by going to Orders and searching for it by code
3. Click the link underneath "Paid using"
4. Refund the payment in your payment provider's system as you normally would
5. If you are giving a full refund, you may want to void the gift card. If you are giving a partial refund you may want to remove credit from the gift card by clicking the REDEEM... button
Please note that Gift Up! fees are not refunded by voiding or removing credit from a gift card.