OSCommerce Small modification in the payment option

In payment option sometimes customer face problem, they entering there Credit Card information and select another payment option by mistake. What I want you to do is to hide the Credit Card information form from the customer until he select to pay by Credit Card. It's a very small modification, more information and details attached. Please note that we will NOT give you access to our site to make the modification, we can provide you the necessary php files you may want, so you should make and test the modification in your server