Overbilling MTN

MTN grossly overcharged my contract account with data charges. Since August 2015 I have received no credible explanation and frankly no client service. Just defensive emails from their so called 'executive complaint escalations'. I am out of pocket with almost R2500 and my service provider since 2001 fails to even care enough to pick up a phone and call me. I am definitely leaving the network as my contract comes up for renewal. When I look at the number of overbilling complaints in the same billing period as mine it cements my thinking. #badadministration=clientspays