Account dishonesty

During the past 2 years I have been a loyal customer of Tracker, having installed a Tracker in my Toyota Tazz. When I sold my vehicle 3 months ago, I was told to wait another 3 months to avoid paying a penalty of R800 which would then be reduced to R400. When trying to cancel it 3 months later, I was told that their fees have now increased to R800... A 100% increase?? Also without notifying anyone. The sales assistant mentioned that many clients were very upset by the change in events.