Hello Steve,
i'm already installing a new shop with your opc included.
I found maybe one error in the payment part.
Every Payment Module I tested that customer input requires, doesn't show the input forms. There's no difference between selected or unseleceted checkbox.
When I delete the elseif-clause
elseif (isset($selection[$i]['fields']) && is_array($selection[$i]['fields']) && ($selection[$i]['id'] == $paymentMethod))
at checkout/payment_method.php, the input forms are shown once.
Selecting a payment method let the input forms disapear.
I spent a lot of time searching my misstake but I don't know how to solve the problem.
PLEASE HELP :)
Tobi