Data Billed Without Being Used

So I have an ASDL line installed and have not used my modem since, in fact it has been locked in a drawer. I have received a bill for R1700.00 for data usage out of bundle rates. I am not the only one. AND this is the second time!!!! When I call the call centre I get told \I can send you a report but you will be charged for it"- of course why didn't I think of that? I was also told to go to a Vodacom Shop where they will be able to extract the information from my modem and log an investigation. Well apparently the man at the Vodacom shop knows nothing about this and on asking what can you do his answer was a resounding \""NOTHING\"". So for two months now I have been billed extravagantly for data not used. Frankly I am tired of this and the lack of interest in resolving my issue! I have 3 contracts with Vodacom which will all be cancelled forthwith. Oh and by the way"