Being charged for promotion that expires 14/09/2017

I am once again sitting with an issue with mtn. I had an issue at the beginning of my contract in August 2016, I was promised promotional data, minutes and sms's for 12 months and the data was never loaded. I had to repeatedly call and go into the mtn store and explain the same story over and over for almost 2 months and it was resolved end of September 2016, when finally they realised I was actually not being given the data I was promised. We're in August 2017 now, a year after my contract was taken out. 11 months since the promotional subscription was loaded onto my account. This month, my statement says I will be debted almost R500 extra for the 2gig promotional data. I understand that the promotion was for 12 months, but I was never informed that I would be paying extra after the 12 months, nor did I agree to have the 2gig continue after the promotional and be charged almost R500 extra on my contract. The promotion should just stop and fall away, like mtn does with the 30gig promotional data at the beginning of some contracts, and not be charged for something I did not agree to having on my account after the 12 month promotion ended.

And according to all the mtn applications that calculate my subscriptions, and the fact that the missing data issue was only resolved in September 2016, the 2gig promotion will only expire 14/09/2017, today is 22/08/2017 and I was already being charged on my statement on the 13/08/2017. All I want is to make sure I will not be debited more than the amount I agreed to pay monthly for my contract. I have called the mtn call centre 3 times and nobody could resolve my issue. I called an hour ago as well, and the associate just said he cannot help me I should go take it up with the mtn store I took my contract out with and see if maybe they can assist me. I do plan on going in, its just really frustrating that I once again have to waste my time, and petrol for yet another issue I have with the same contract with mtn.