Months and still no proper response.

I have a 5GB internet data contract with MTN and get charged R279 pm. I then got a bill for almost R1,200 in March, then another for almost R1,000 and then another for R338. I queried why my bill had increased so much, particularly as I have the Night Data deal for extra 5GB pm.<br> <br> Almost 50 days later, I was then told I used 24GB in March, 10.2GB in April and 4.4GB in May respectively, hence my increased bill. When I asked them for a breakdown of how they came to this, I got no response and am still waiting. How could I be charged extra when they told me I used less than what I pay for in the 3rd month? That is either pure incompetence or *******, maybe both.<br> <br> I write this in the hope that someone might finally be able to answer my questions properly. If not, I am going to request they cancel my contract.