Cancellation for our Matrix tracking system (Mix Telematics) that they still deduct money

I cancelled our tracking and recovery at Matrix, because we sold the vehicle, in October 2024. I received a "Confirmation of immediate cancellation" from Telematics on the 28th of October 2024. But still every month thereafter they still deduct money for the tracking system from our account. I did send an e-mail again on the 9th of December 2024, no reply. Again, I mailed them on the 11th of December 2024, still no reply. I would like to know do I need to open a ***** case. They don't answer any phone calls from us, and they don't reply on any e-mails. How do we stop them to deduct money from a service we don't need anymore. They send an e-mail for the cancellation???? Do they take money from other people as well. To do a reverse each time is a banking fee that we have to pay not Matrix or Mix Telematics..