Not honest and full of ****

I have joined nester tracker in 2019 and never missed the payment until last year 2023 when I sold the car and called them to cancel my monthly contract as the actual contract was expired.i even emailed on July for cancelation but no one respond my email and today they want to charge me lots of money while they only respond my email this month 2023. They are cruel and ungrateful after all those years.