Cell C and their *****ed handling of a client

I had a contact with cell c many many years ago The contract was canceled and paid up. Then few years down the line they started to debit my account. Paid and canceled. Since June 2023 I am again being debit whenever without my or my banks authorization. I cannot call because I fail security checks because they have old information except for my bank acc details. I get messages from the debt collectors and if i call them i either cannot reach them, the line gets disconnected or they simply tell me to call the exact no that i cannot get through because of the security checks. I left emails so hopefully someone will answer and put an end to the ridiculousness. *****ing from unaware clients