Theft /********** debiting of funds from account

I received three invoices from vodacom since November 2015, I don't always check the email with the invoice attached as it is a debit order payment, but my contract was coming to an end, so I went through some of my previous invoices, to my dismay, I was beeing billed for content services, what content services I have no clue, and vodacom has a double opt in feature to avoid mistakes happening, we'll I never accepted any content service or for that matter received anything. The amounts debited grew exponentially over three months and lost almost R6000 in three months. I would appreciate a reply from vodacom to explain how they authorised this debit order without the my concent, I am thinking of opening a ******** case as this isn't small change to me or anyone for that matter, and I want some answers, I tried approaching the staff at vodacom craighall and just got laughed at by the staff, and they said it's happening all the time... I'm left feeling helpless and definitely not considering renewal of my contract