Incorrect data charges not being investigated

I have logged countless queries with the billing department about the data charges being incurred on my account being incorrect in light of my phone always having data bundles. These charges range between R1000 -- R4000 and have been incurred over roughly 6-7 months to date since inception of the contract. Every time I have raised this with the billing department I was informed that there is a separate team which handles these queries and that a request was accordingly being forwarded to the responsible parties. In a latter encounter - it was found that a previous query was not forwarded on despite having been captured on the system. To date - not once have I received any correspondence from this illusive investigations team - to explain what is going on with my account charges. This is ridiculous - I am being ********** and I have no recourse available and MTN is not even attempting to solve the problem.