Bad service fro Cartrack

My husband sold his car to We buy cars in May. According to Cartrack they removed the Cartrack equipment after the car the car was sold to We buy cars. Every month they keep on deducting the monthly fee. Every time my husband has to go to the bank to reverse the amount. He stopped the debit order but they keep on putting different amounts through. How does this happen? If you call the call centre they shout at you. What is he supposed to do?He is Frederik Johannes Grobler. His phone number ***. All the costs of phone calls, visits to the bank. What else is he supposed to do? Regards Reinette Grobler