being over charged

I call cell c regarding the billing of my open line which was put on R50.00 limit but now I have to pay R119.00. Puleng Mogale he tells me that I'm using too much of data, but I hardly use that line and I asked him that I normally get sms saying that my data bundle has been depicted. I ask that what does that mean he told that I must consult my dictionary but what is he doing there. The TM corny I asked her how come can I put limit of R50.00 while I'm gonna be charged R119.00 and she sad to me an open line it is a open line, I asked her ' I need them to pull out a call when I was called about that contracted ' she sad I must give her there date but I think it has to show on there system when I took it as they can see that I'm using data bundles that I don't normally use. In short poor service from agent and there TM they are clueless which what they are doing I even told my lawyer about this I won't pay that R119.00.