I have a Order that is in Pending Payment status. The payment has been taken by Worldpay but the payment response message failed.
How can I complete the order and change it to paid?
To complete Order you need to generate invoice for that product from backend.
Open Sales > Order tab and open product which is pending and you want to make it complete.
Generate invoice order status will be changed.
I have just done that and an invoice has been created by it still says Pending Payment in the admin... so I can't complete the order.