Wrong billing & I'm not getting any help from them

Took a data contract in May with Cell C of 5G during the day and 15G at midnight. When I was billed over R2K i called and ask why so much money and they told me that I have used the data. I then asked for itemised bill. When I got it I recalculated all the data that they say I have used. I calculated day and night and I realised that for the day I used less than 5G and midnight less than 15G. I told them and they said you get charged even if you still have data if you watch and/or download movies, surfing the net, watching you-tube. I told them that my contract does not say that and even when I took the contract no one explained those terms & conditions. I have 2 contract with them, since I was not will to pay that R2294 they suspended both my contracts. In 23 October they deducted that R2294 but still my both contracts are suspended even now as I write to you. I have the bill and you could see that I am charged more for using less data and charged less for using more data, this does not make sense. I am so stressed, so angry so frustrated and want to sue Cell C as this has affected me so badly, I have seed my GP, she referred me to a psychologist. I have wrote to ICASA as well.