No contract but bill every month

I had two contracts with MTN, I then requested to cancel contract 1 on the 2/7/20. Portia canceled contract 2 by mistake on the 5/08/20. I requested Thando on the 12/08/20 to correct the mistake but contract 1 was canceled on the 19/08/20. Which ultimately left me with no contract. However to this date MTN still bills me every month for something I do not know. ☹☹ MTN can you please stop billing.