Matrix Harassment

I purchased a vehicle and collected on the 30th December 2022. I decided to take a policy for a tracker with Matrix. I drove the vehicle the whole month of Jan 2023 without a tracker. I called them and they only came to install the device in Feb. I started paying end of Feb (if not mistaken)

At the end of May 2023, I decided to change and buy a bigger vehicle. I then decided to cancel my policy with Matrix. I sent them an email to that effect, there was no response. I sent another email to which the responded telephonically. They told me I can not cancel, citing reasons that, if I remember well, the duration was too short. I told the lady that I don't need their services anymore and I don't have the vehicle in my possession anymore. She insisted I install ANOTHER device on my new car, and continue with the policy, to which I refused. They continued debiting my bank account, and I had to reverse and put a stop order for months. They continued changing references and debited my bank account for a number of months, which I consider as theft. If you take money out of someone's account without permission, that constitutes theft. They continued harassing me with calls and eventually handed my name over to the legal representative for collection. So I need assistance. How do I deal with this matter. Is there anyone who can assist me.

Thank you in advance