MTN Worst Services ever!

I cancelled my contract with MTN in November 2024. The account is closed with MTN. I cancelled the insurances with Admyntec the same day as well in November. From November 2024 to date admyntec is billing me non stop. I phoned them the cut the call on you and blame it on the line services. The manager has not responded to me. Where are they getting a billing for on a closed account? Can this get any more stupider??? I was so fed up with MTN and admyntec that I had to cancel their services after 35 years of beign a customer. Then admyntec has the audacity to ask me to go to MTN to get an invoice which i did. MTN said the account is closed on their side and they cannot provide me an invoice. Now they ADMYNTEC dont know how to answer me. Can anyone believe these ridiculous services? 6 month after cancellation i am being billed monthly. That is not a system error. It is a human incompetence.