Unauthorized Debit order Date and Amount

Telkom has been deducting amounts from my bank account without my authorization. There's no debi check sms sent for deduction amounts and they deduct in any date without consent. I was given the most disgusting service when I called to query. Also I had disputed my debit order because they deducted 3 times the amount that I had approved via debi check, thereafter 10days later they decide to deduct double that amount that I disputed. The reason I disputed was to query why my bill was so high and how could they deduct such a large amount without my consent. Is this even allowed? I would never advise anyone to take a contract with Telkom. Their customer service agent says that they will continue to debit without my consent...any amount...anytime. I would like to know how this is allowed after 10 days i disputed to query? They lack basic communication. There's been no communication to inform about any debit dates or amounts.