Double charged me for years! Disinterested Customer service

Netstar charged me for the same vehicle on my BOTH my personal and business profiles for over 2 years - essentially double charging me to a value of over R4000. Only because I caught this has it been stopped (hopefully). But they have not responded wrt the refund due. Also they kept charging me for 3 vehicles that I sold many years ago with units that are not working and/or not moving - surely their system can pick up dormant units but they are only too happy to take my money without providing a service and their customer service doesn't seem to care. I will be cancelling Netstar trackers on all my vehicles.