Go to the Sales → Orders
You have the ability to initiate a refund action from within your payment processors dashboard, but some advanced Payment extension allows you to refund/capture directly from within your AbanteCart Order edit page. If your Payment extension allows refund within AbanteCart on Order edit page will appear Payment Details Tab. This option is available only for advanced payment API integrations like CardConnect, PayPal Pro or Advanced Stripe.
You can also issue a store credit to your registered customers. To do this add new transaction on customer page.