MTN is *****

I recently noticed a debit order of R721 by mtn on my cheque account, Fortunately at that time i had no funds in my account because im unemployed the debit order bounced off so many times it caused my account to be on a negative, i thought it was a mistake, guess what another debit order last night and this morning bounced off a different amount of R360, 89.. This is affecting my account negatively as i have been charged some overdraft fees and dishonoring fees, I NEVER OPENED ANY ACCOUNT WITH MTN AND WHERE DID YOU GET MY ACCOUNT NUMBER? AND AUTHORITY FROM TO DEBIT ME?... I DEMAND SOME ONE TO COME AND EXPLAIN AND SORT THIS ASAP OR IM TAKING IT FURTHER.