To refund an Individual Booking, from the Retail Point of Sale Screen:

Select Bookings.  The Booking Screen will now appear.  Locate the booking you wish to refund and open the booking as below.

In the Ar column to the left of the name, double-click on the box which currently has an 'A' to view the drop-down box.  In this box select the option 'R'.

In the toolbar at the top of the screen you will see an option F9 - Arrive.  When you select this option the refunded charge associated with the booking will be entered into the Point of Sale Screen, as below.

You can then refund the money by selecting the payment button on the screen or by selecting the applicable payment method on the keyboard.