268053 Oscommerce payment module

I want an option in a certain payment module for oscommerce. The module is already there But needs a modified clone which will have the abilty to prepay a certain amount depending on the order ammount, so that the rest ammount is paid on delivery to the driver or postman. 0-100 euro is prepay all 100-500 50% prepay 500-1000 40% prepay 1000-2000 30% prepay 2000 of meer 25% prepay Example: i order a product with 600 value, i have to prepay 40 percent =240 euro, restammount of my invoice will be 600 - 240 = 360 euro the used module is IDEAL for the Nethelands only.