To refund or issue a credit, logon to your Admin Panel under Sales Activity - Recurring Sales. Choose the Order # of the Sale you want to refund, and click on it. This will open the Order Details page. Scroll down to the bottom, choose how many installments you want to refund, then click Issue A Credit.

To stop a recurring payment, logon to your Admin Panel under Sales Activity - Recurring Sales. Choose the Order # of the Sale you want to stop, and click on it. This will open the Order Details page. Scroll down to where you see Stop Recurring Billing and click on that. Once you click it, your customers card will not be billed again. Keep in mind that it can not be undone!