Developing/ editing the Worldpay payment page

[stoo_s]

Our site uses Worldpay for payment and the system is secure and works really well but I'm concerned that it is losing us sales due to the redirect to a worldpay payment page that looks old and completely different to our website. I'd like to edit the payment page to look like the rest of the cart/payment stages that a buyer clicks through but don't really know where to start. Does anyone have experience of doing this or know of a dummies guide to it? I can't find anything on the forum.