There are two options for changing a redemption rate for a customer,First option would be giving that customer a special rate or the other or the next option would be

First you need to select “Retail Menu”, just like the image below. then once you have done that select the “Refund and Layby Cancellation”, like the image below. Then you

At the Main Menu, Select the “Till Balancing” Then Select the button Redistribute Payments like picture below, Then Select the tab that you are wanting to do “Loan Payments”, “Retail