Pay more attention to your customers and just be honest

They have been debiting my account for months without my consent, approval, receiving any service from them for this debit. I have sent umpteen messages to find out what it was for and proof of me requesting this service. To date I am still waiting for a reply, or a message regarding this. They have now stopped debiting my account but no explanations on why and for what. Where fid they get my banking details? Multi choice???