Charged for Data not used

I upgraded my account with Vodacom earlier this year. I received a new sim card and never used it until 21 March 2015 this year. I received a bill from Vodacom for data usage to the value of R1276-16 used in February 2015!!!! How can Vodacom charge me for data even though my sim card was not even in a device. <br> <br> I reported this to Vodacom on 1 May, 3 May, 4 May and again on 29 May and today and I am still waiting for a response regarding the investigation as promised. I am now getting letters from Vodacom saying that I will be given over to their legal department if I do not pay. According to Vodacom I used the data and that is it, there is no evidence or proof that they can show me. Even my device shows that the sim card was only used as from 21 March 2015, not a day before that!!!! PLEASE HELP ME, how can Vodacom expect me to pay for data that I never used?????