When the payment is a gift card and an error occurs during the order placement process and the order remains incomplete, then the GC is not refunded after the transaction is canceled.

This issue was first discussed in this thread and basically, there are 2 operations managed by the GC system where this issue might occur:

1. When the amount of the gift card is debited;
2. It then saves the transaction info in the SimpleDB.

Refund manually via the Gift Card UI.