Cartraker is refusing to cancel my tracker

I have installed the car tracker for more than years and last year I have pick up that the tracker is not working.tracter send the technician to fix it two months later sometime happen.Now again is amongst 6month.last month I called to cancel and requested reference number.they could give me.i have received the call again regarding my cancelation but they don't cut it.they keep on sending mail that they try to call me but they can reach me.