3GB Bundle Not app****

I knew that I was going to use a lot of data in a month so I bought an extra 3GB package for the month and then later another 1 GB package in addition to the 3GB I usually have for the month. I got a bill dated 1 September 2015 with invoice number *** in the amount of R3355.19 despite this. When you look at the Bill it is clear that under the heading of monthly charges that only my usual 3GB package and the 1GB I bought was taken into account. In other words the additional 3GB package I bought was not taken into account and I was billed at out of bundle rates. I explained this to cell c but they only respond that they have checked the amount of data I have used. That is not the issue. The issue is whether the additional 3GB package I bought was app**** to my account. Cell c has failed to address my concerns and has not furnished me with a clear indication of how much data I used when I had effectively 6GB of data to use.