Refusal to cancel contract that's already expired

I have been struggling with this company since Oct/Nov 2025 to cancel my contract.....they just keep ignoring me and then I got Hello Peter involved and got a response from them the same day......after some back and forth correspondence and explaining that my contract was originally only for 24months and I am very close to 36 months so I have all the right to request/insist on a cancellation, with an extra fee because I am not canceling in the required 24 month period, they agreed to a last payment of R219 and I will be rid of them.... in these almost 36 months of being their client I actually tried to use their services ONCE only to be denied access to my app and refusing to give me a new password......I had to contact an alternative security company to track my car with only numberplate recognition..... totally ridiculous.....I paid the requested amount of R219 and it felt so good to eventually be rid of them, only to receive an invoice and email from them saying I owe them money and my 36 months is not done!!!!!!! I absolutely refuse to pay them one more cent and don't every want to hear from Matrix/Powerfleet ever again.....please assist me in this ridiculous mess.....thank you