Incorrect Data billing

I have a contract with Vodacom and I once received an SMS that I owe about R5400 for data that the say I used I never used that much data and I`m staying in Tshwane where we have free Wi-Fi so there is no way that I can use this too much data. I tried to call Vodacom Customer service the don't pick up their phones.<br> <br> Tried to email them still no luck. And they deducted that much amount from my bank account and I went to the bank and made a reversal. Then I went to Vodacom shop in Pretoria central to stop the debit order so that I can pay mannually, they faxed my request to their head office, but still my request was not granted. <br> <br> Then 04/0/62015 Vodacom di-activated the data bundles and the tablet is no longer working, and I did not receive the data bundles even before this date. <br> <br> Today I received the letter from Vodacom saying I owe R11557.15. And I have to pay it within 21 days. My question is for what? As this is not working and id did no work for a very long time.<br> <br> They can come and take the Tablet as its no use to me. They can even terminate the contract. <br> <br> I`m not happy with their service.<br>