Mtn Cheats me into paying R2/mb on data

I bought Xbox One and had to download a 2Gb update before I could use it. SMS messages from MTN earlier the day state that I received 1GB of data, as well another 1GB free since my billing cycle is from the 15th to the 15th. This day was the 15th of Sep 2015. So I phoned Mtn to confirm how much data I have. Spoke to a Sharon, who confirmed that I have 3Gb available, she even noted it on the system for the next call centre agent. I then used my phone to download the update on my new XBox, only to get a SMS stating that I have gone out of bundle. I phoned MTN who confirmed that my account will be suspended and that I went out of bundle. My account will now be suspended from the 16th this month to the 15th next month, AND I must pay R2/mb for 1GB of data. Only then they confirmed I only had 1GB data in actual fact even though my previous conversation with them confirmed 3GB and even though SMS messages from them confirmed 2GB. I use CellC data at 1c/mb, I will never ever agree at paying R2/mb. I think this is the end of the line for me and MTN. The lie from the call centre agent will cost me over R2000.