Once again a Vodacom issue where they just take money from your bank account.

In June I upgraded one of the 6 contracts I have with Vodacom. My normal instalment is R1750 monthly. The upgrade contract is (Or was supposed to be) R179.00 per month. At the end of June Vodacom deducted R3749.00 from my bank account without my consent. That is R1999.00 more than my normal instalment. I then phoned Vodacom and asked them why this happened. Please bear in mind, this is not the first time this happened to me with a Vodacom upgrade. As per me, it was just a straightforward upgrade. I was informed by Vodacom, that they billed me for my phone. They never told me that I will have to pay R1999.00 for the phone. I am now busy with Vodacom for two weeks and still, no one can help me with my issue. I was taught that if you take money from someone without their permission, it is theft. Can Vodacom get away with this?