Not pleased with cell c service

I have a cellphone contract with cell c as well as 2 sim only sim cards for 10 gig data each. The sim only deals were offered at R129.00 each. And I thought this was a good deal until my first debit order went through of R984.00. I called cell c to find out what this money is for and they told me that I used out of bundle data that is why I was billed this much. I was very specific about what I want and don't want from cell C. I specifically told both agents when my data run out, I want to be able to top up and in that way I have control over my spending. This was not done. The second month, I was charged just above R700.00 for these contract that were sold for R129.00. I called again requested statements for the two simcards and to lodge a complaint. I didn't get a statement nor response on my complaint. Every month I have to call cell C for the same things. One wouldn't think that such a big company would **** customers. The R129 deal was too good to be true. I'm ever sorry I took it.