Incorrect billing, two different limit to be set on an open line account

have 2 contracts with cell c, and I requested a limit of R50 in each account that was in December 2015, in january when I checked my balance it showed that I had to pay +-R950. I called to enquire and I was told that I only set 1 limit and there are 2 different kinds of limit. I asked the agent to then set the second limit on both account and it was done I even received an sms confirming dat. and in January when I checked my balance it showed that I had to pay R624, again I called to enquire and spoke to Mawande Mlotshwa who says both limits does not apply to data, I was now confused because in January I was told that 2 limits where set and they will not exceed R50 in everything but today I'm told that it does not include data. please assist in reviewing the calls I made because they are my only proof, because I paid the amount in January but I'm not going to pay for your agents mistakes. I'm so unhappy with the service to an extent that I will never recommend cell c to anyone. are my only proof, because I paid the amount in January but I'm not going to pay for your agents mistakes. I'm so unhappy with the service to an extent that I will never recommend cell c to anyone.