overcharging

On the 10th November 2018, I had to do an upgrade against my better judgement. I opted for a made4business contract for R349 as advertised. It includes 500sms's,200min and 5GB data. Since my first invoice in December I have been battling for MTN to sort out the billing which is being billed just over R900 a month, that is a huge difference. To date I have yet still to have someone call me regards the overcharging, they are quick to cancel my data, calls and sms's because I had my bank reverse the last two debit orders. They(809@mtn and the store- Canal walk) agree it is an error on their side, but no-one is fixing my billing situation, so they keep taking off between R800-R900 a month. I have been into the store twice and have sent numerous emails to the 809@mtn email address, still to no avail. As at today, there is no resolution and this is 5 months later. This is absolutely ridiculous that as a consumer we get treated in this manner with no repercussions from their side, my business has suffered as a result, not to mention how much time and energy I have spent trying to resolve the issue. It just seems that there is so much finger pointing and no one is taking responsibility for their incorrect actions!!!