Come remove your tracking device from my car

If you have a car please stay away from Car track , they honestly don’t know how to treat there customers,firstly I’ve been with them for more than 3years and I’ve never asked them for anything but kept on paying them ,so early this year I got a better offer and asked them to cancel my contract of which yes they did and asked for there last payment for that month and I payed but had to reverse the payment because no one was taking me seriously when I told them to come remove there tracking device as much as they came to my house to install it. I don’t understand why should I go to there office to remove my tracking device but when they installed it they came to my house like doesnt make sense at all , now they threatening to black list me because I don’t wanna pay them 54rands but they still haven’t came to remove there tracking device and I sent them emails not once or twice.