Grossly overcharging for data on a fixed 2GB accou

In May an amount of R3290 was deducted from our account for an MTN 2GB Data account that should have cost in the region of R150. On one of the few occassions I was able to get through to the call centre, I was sent an invoice by email so I could see which one of our 4 services on the business account racked up such a huge amount. Unfortunately it doesn't supply you with anything else than a billing total. I requested for detailed billing for this specific data service as it is impossible for us to have used that much data. A call was logged (ref ***) and escalated to the Billing department on 30 June and I was supposed to have received feedback from them within 3 days. I am still waiting and its impossible to get through on the call centre number. My follow up email sent on the 3rd July 2015 was fruitless as well. This is ludicrous that MTN can charge clients such huge amounts for data and deducting the payment from your bank account without providing proof of where the charges are coming from. On the email copy of our invoices (which we haven't received via post since April) even our physical address has been changed. Feels like somebody didn't want us to receive the invoice