Unfair Billing

At the end of January 2015, I was horrified to be billed <br> <br> R1 921.66 on my internet account with Cell C. What am I being billed for here??? There is no way I have used this amount, as on the very rare occasion that I have run out of data, I have bought data bundles. I use my data when I am out of home, or, during load shedding periods.<br> <br> I have wifi at home, I live alone, and no one else has access to my laptop! If you look at my usage history, I have NEVER run up an account.<br> <br> I have been into Cell C countless times, sent emails, and made phone calls, only to be pushed from pillar to post! I am tired of getting no satisfactory answers!