Overbilling of my account

MTN has over billed my account with an amount of R3852.89 where my average monthly spend on the data card is R170.10 per month, how do you justify that amount in one day the accrued spend is almost R2000, not possible.... Also when queried the issue its being told or said that the matter has been escalated? since the 08/07/2015---- surely there should be some outcome by now.<br> <br> MTN ***