Money debited for non-existing/canceled account - no support or assistance available

I canceled 3 Vodacom contracts last year in October. Afterward, money was still debited from my bank account. After speaking to a few different consultants, one finally discovered that I was charged for a contract/number that should've been canceled years ago. She canceled the contract/number at the start of 2020. She also confirmed that there would no longer be any charges debited from my account. Debit orders continued. I wrote emails to their dispute department (as suggested by one consultant) with no response. I blocked the debit order and are now sitting with an account in arrears. No one can tell me what it is for and no one can assist.