Extremely High DATA bill that cannot be resolved

We received an extremely high DATA bill in June this year, I asked for the URL's which took 3 months to receive. Most of the data was at night when my office is closed? my average spend is R500.00 and the bill in June was R21,227.29. They only contacted me to tell me that I have high usage when it got to R16,000.00? They also then tell me that the out of bundle rate was increased from .22c to .45c almost double the normal amount which I have no correspondence for? I have asked so many times to look at the account so we can fix the problem but it seems they just don't give a damn. No one ever replies to my mails that I send. I have being reversing the payment every month until we can come to a compromise. I could understand if my bill was high every month but this is a joke. I also had the same problem with my phone. No settings were changed but was still eating data. When I started monitoring the usage at my office we were using 2gig a day? on receiving emails, something is wrong but MTN does not care. We are a small company and cannot afford this, but would like to resolve the issue but we have not been met with any level of service from MTN