Matrix mistreating it's customer

I had a prepaid 36 months contract with Matrix-Beame which ended in September 2024. The contract (Beame Customer Data) indicated that after the 36 months, we will work on a monthly subscription fee. Thus on September 18th and October 4th 2024, I received SMS messages requesting that I respond with 'agree', if I wanted to continue with their services. I did respond with 'agree'. However, upon receipt of the same message on November 22nd 2024, I responded with 'no' and stated that I had traded in the car. I didn't receive any response or call regarding that response, only to receive calls in January 2025 that I owe the company for non payment as from November 2024. Although the consultant agreed that their system shows my November response, the company continued to insist that I owe them and that I should send a cancelation to a specific email address and the cancelation would only be effected in February 2025. The monthly SMS never indicated that. Now they are threatening with blacklisting me. My email of January 13th 2025 where I detailed my reasons for believing that I don't owe them, and my follow up on 2 occasions has not been attended to. I see this as an unfair practice aimed at bullying customers. Their SMS was misleading and there was no effort to advise the customer after seeing the 'no' response.