Oscommerce Payment Page Edit

Hi, We keep getting orders from people who didn't mean to use that payment method. Whats happening is they enter there credit card info which is the default payment method on the payment page, and then select Interac Money Transfer or Paypal payment method which is listed below and then follow through and complete the order even though they didn't want that payment method. Then they think they paid previously with a credit card and want to cancel the order or they just don't send payment. So what we need is a message that pops up when they change payment method. The message would need to be customizable for each payment option. So for example the default payment method is Credit Card when they click off of that to use paypal a message would pop up saying: Would you like to change your payment method to Paypal? The customer would have to select yes or no to change or not to change the payment method. If they select no then nothing would change if yes it would then use the new payment method. We don't want the default payment method to pop a message unless they click of that payment method and try and go back to it after. We do have a test site so you can test on the server. We would like this done ASAP but will not pay a lot for it as it should be an easy fix.