Cartrack

I am not happy at all with cartrack, i sold my car and i wanted them to give me the forms so that the new owner can continue paying but they told me to pay R350 , surprisingly i was not told about such thing, another thing they deduct money anytime they want , and they increase the monthly instalment every year and thst was not our agreement, since last year am waiting for the record they promised to send, please help me with cartrack am so fed up with them