Unfair billing due to i-net cap malfunctioning!

I've been on a databundle contract for years at a rate of about R150. Then suddenly I received a few bills for R300 odd. So I went to the MTN shop in Tygervalley twice, and emailed customer service.<br> <br> Eventually I was informed I could change over to a new contract for R119 a month that gives me 2 GB/ month and on which I can add a cap to ensure that I never unknowingly use up more data than my contract allows for. I instructed them to cap my data usage, which was done at the shop in Jan.<br> <br> Between then& now, I received random extra invoices via sms. So obviously I went to the shop again today to enquire after my internet stopped working, which I assumed is the cap.<br> <br> So turns out, I have a R700 odd bill on top of my normal fee. And a second invoice of over R1000 for next month. So the cap was not working AT ALL! and I have to pay ridiculous rates because of this technical error on MTNs side. I kindly ask you to come up with a humane way to let me pay for these bills which I really can't afford as the whole point of my numerous visits to the store was to reduce my expenses. I was more than willing to buy new data bundles once my 2GB ran out, at the way more affordable bundle rates.