We've had a number of circumstances where customers for various valid reasons have requested a refund for a gift voucher order and we've issued an RMA for the payment. This means that the voucher itself needs to be cancelled so it can't be used any more but marking the voucher inactive in the vouchers screen doesn't work... so we have a situation where the customer has been refunded for the voucher, but the voucher is still available to be redeemed. There seems to be no way cancelling a voucher other than using it for a dummy sale to fully redeem it - which affects sales figures.
