MTN NOT RESPONDING TO DATA CHARGES OR EMAILS SENT

I have a problem with my account with MTN and have been trying to resolve it since February 2015 with no luck. I have been speaking to customer care on a regular basis and logged calls to investigate the problem on my account.To make matters worse, even after I logged the query is that my phone then gets cut of due to the outstanding bill. As I am typing this email, I received another SMS that my services will be suspended, this is UNACCEPTABE as this is the phone I use for bussiness, please resolve this urgently.The problem started in February 2015 when I received invoice for the amount of R6 976.08. This is impossible as the data charges for that month was R4 330.27.My monthly bill since I changed my contract at MTN (3 years ago) has always been R1638.00 per month or R1738.01 (when I transfer R100 airtime to my daughter). March invoice was R21,326.46, again data usage of R16,410.14, again impossible but no one seems capable to resolve this. I need this resolved as it is impossible that I use that much data. When I am at home I use WiFi as I have unlimited package with Telkom/Mweb. Why did my charges change and items on my invoices?