Netstar *****ing money

I sold a car and cancelled my netstar contract in December of 2022. After many fights and unanswered emails I finally received acknowledgement when I stopped paying. I received an email apologising that it had taken 4 months for the cancellation request to be handled, but was assured that everything was now in order. Netstar then continued to debit my account. I rejected the debit orders, and now 6 months later I am being threatened with being blacklisted by NuDebt if I do not pay within 24 hours. Sounds like ******ion to me and bullying to me...