As we process payments across a variety of different payment methods, not all of which are able to be refunded, we don't provide for the ability to refund a transaction through your account.
We do have the ability though, to refund credit card payments (and EFT payments to a lesser degree) through our administration system and we can process these at your request. That is to say, it is needed to resolve an issue which has occurred, rather than being something built into your business model.
If you would like a transaction reversed/refunded, please just get in touch with our support team, who will be able to assist. Have the name of the buyer available as well as the amount and the reason for the reversal.