Vodacom sent me on an errand for an error that’s on their side

Vodacom had taken money from my bank account for the past 4 months via debit order. I don’t have an account with Vodacom. When I called to find out how this is happening, I was told to get an affidavit and bank statements and go into a branch and they would investigate on their side. Why do I have to go through all of that when I do not have an account with them? Please stop taking money from my account.