Netstar: bullying ******!

I've sold my one and only vehicle on the 21st of June '22. Immediately after the transaction, I cancelled my insurance with DialDirect. Then, out of the blue, Netstar started hounding me - with tales of outstanding duration of contract. I NEVER had a contract with Netstar! The tracker that had been installed in my vehicle, had been the doing of my insurer, Dial Direct. Since then, Netstar keep pushing debit orders through my account - that I have neither agreed to, nor signed. In the 3 years I had the vehicle, I've never heard a peep from Netstar. Now, all of a sudden they keep bombarding me with sms'es allerting me that the tracker had been tripped on a vehicle I don't own, does not carry a registration number that had EVER been linked to, or owned by me, traveling in a Province I don't reside, nor travel in! I keep phoning them to tell them :"NOT my vehicle!". Upon which they refer me to cancellations dept. But... That call NEVER gets completed! They always manage to disrupt the call, before completion. When I complained about that, in one of my numerous calls, they promised to send me an e-mail to facillitate this cancellation. IT NEVER HAPPENED! NO E-MAIL EVER SHOWED UP! Now they have the audacity to threaten to blacklist me!!!