Bill going up for no reason

I have a Epic 150 contract with cell c. For the last 2 months my mobile data has been turned off and I only use wifi for data. Yet my bill is still coming in at R150 + over my monthly contract amount. I am not making phone calls that would amount to this much. I phoned your customer care. Before I called my balance was showing R94 airtime. After speaking to her and her putting me on hold I all of a sudden had a R0 balance and was R97 over. Please explain this? I have dialled *133*1# and I am not subscribed to any services. I want this rectified asap. At current I am looking at cutting my losses and paying in to cancel my contract before more costs are run up at my expense.