BidTrack trying to pull a fast one on me

I traded my Nissan Qashqai in on 15 June 2022. It was fitted with a BidTrack device. I'm now being called by an *** number, informing me I have an outstanding amount from my October 2022 statement. How is this possible when the car was sold? I'm now being threatened about my name being blacklisted. I refuse to pay and if you want to blacklist me, go ahead. We'll meet in court.