Very bad customer service from Cell C AGAIN!!!!

Cell C is up to it again! I upgraded a contract line in November which became active in February, also upgraded a data cash contract in February. When I received my billing advise on the 6th March, I was overcharged on both accounts. I immediately called the call centre and was told that pro-rata rates apply. I asked how I could be paying more on the new contract of R215p/m or thereabout compared to the old contract of R409. On the data line I just did a package change to allow more daytime data, the price remained at R199. Lo and behold, they bill me for an amount of R298.50. I have asked them to resolve this before the debit order goes through which they have not done. Even after receiving sms and email confirmation that it would be sorted by Friday 16/03. Every time I have to call and fight with them as absolutely no-one at Cell C is interested in customer service. They don't even know what it means. All they have are call centre agents working from a pre-scripted response sheet that have no idea what's going on or have any intentions of assisting the clients. I'm so sick and tired of Cell C and their bad service. If they don't come to the party soon I will have to take more drastic action.