Vodacom charged me R2 300 in data, in just 3 weeks

I opened a cellphone contract on 9 August 2015 and I was unknowingly put on an Open Line contract. 3 weeks later, Vodacom said i owe R2 300 in used data, in just 3 weeks! My phone was then put on soft lock and i could not make calls, send an sms or use whatsapp/ access my emails. <br> <br> I went to the Vodacom store in Sandton and called Vodacom's customer line but I got no help, even when i told them about my data usage. I used wifi at work (Mon-Fri). I could never have got to that crazy amount of R2 300, using data alone, in just 3 weeks. I am not a business. <br> <br> I want proof of this otherwise I am taking this up with the relevant regulators and I am not willing to pay so much on data charges. It's ridiculous. The Consumer Protection Act was implemented to avoid such exploitation.