debiting my account for the unit that i no longer have

good day , I had an account with cartrack and I sold my car and when I did that I phoned cartrack to let them know so that they can go take out their tracking unit from that car and I was dealing with Jim Makubjwana they promised to do so but to my surprise I think they did not because they keep on debiting my account and just yesterday I received an sms saying my tracker was tested and it is still in good condition I don't know what they were talking about . I need this to be resolved as I don't want to be debited for nothing anymore.i have emails that I sent as a proof pls help me