Log into Worldpay main site (select MOTO from the list)
Click on payments
Select the appropriate account (Usually the main WPACC8480565)
Search for transaction
Click on the link from either the transaction ID or the payment amount which will open a new window. (you may need to scroll the page up as it always opens near the very top.
Scroll down to find refund and ensure you change the amount if you are not refunding the full amount.
In the billing find the corresponding invoice and click on refund from the tabs.
Select manual refund and check the amount.
Use the same transaction number placing R- in front