Billing of Data usage

I took a contract phone with Vodacom in 2012 December .Put in notice in December 2014 and informed me that this will go through in January. I have not been using the Sim card with the number *** on a regular basis, as I would only make calls every now and then . my issue is the date usage , I have not been using the data and when I requested for the invoice I got a huge amount of money that I owe for data usage and I do not understand how that can be possible as I was not using any data from the Sim card***) <br> <br> I am not happy with the matter and am failing to understand how such can happen , I feel like someone is not doing their job , I cannot pay for service I did not enjoy. I need this matter resolved as soon as possible.