Need a System that credits users and accepts minimum payments ($100)

[Elevenbravo90]

I am in need of an extension for VM 1.1.9 that allows me to offer customers a 500 dollar credit limit. This credit limit has to allow user to purchase items with it and automatically subtract the difference. How it works is that when a user buy an item: for example item a is normally 100.00. With the credit line you only have to pay 30% out of pocket (30.00 up front) and your credit line ( the 500 dollars) takes care fo the remainding 70% (70.00). So that 70.00  that was spent needs to be subtracted from the 500.00. At the end of the month i need it to take the 70.00 you spend and break it up in a certain percentage to calculate the minimum payment due. so say minimum payment is 10% of your balance of 70.00 minimum payment would be 7 dollars. after that minimum payment is made i need the program to add that 7 dollar payment back to the credit limit. so 500.00 - 70.00 = 430.00 plus the payment it will bring the total back up to 437.00. I also need an option to allow people to pay the balance off in full....I will pay good please email me with a phone number and a good time I can call you. Renegadeco.1@gmail.com