Contract not explained properly

Hi <br> I took out a 2gig contract last year, when I took it what I understood was that every month I get 2 gig of data. What I didn't know about it and I found out now when I spoke to Pontsho fom the call centre today, is that there is something called a night time express data for 2gig that came with the package. My problem with this is that when I check my balance, it doesn't differentiate between the night data and the day data. I have recently run up a bill of over R600 because of internet usage coz everytime i checked my balance I had a positive data balance whereas it was the night time balance, so I'd think Im well within my data spend except I am running a daytime bill on the side which I am unaware of. This is an ommision from MTN which has cost me a good R600+, how are we going to rectify this grave costly ommision because I did not know about this up until 5min ago,and no-one from MTN made mention of this before. I do get that MTN is always sorry about these things happening etc etc, but can we please come up with a solution and a response that will make sense to me other than a standard PR apology. Your ommision has cost me money, I want my money back