Unacceptable double charges

When upgrading to the my200 contract on the 12 of February 2015, at mtn diamond pavilion, Kimberley. we asked the consultant to place a limit on the contract, she then placed the limit for R1 on the same day and informed us that it was confirmed. Once the airtime and data was depleted the Internet and calling services were off until I recharged using my FNB account multiple times, of which I have proof. Yet For the month of February the bill was then 2300 and March R5600. We continued to call customer services and they informed us that the limit was only placed in 28 March 2015, and that the outstanding balance are data charges. However the Internet went off as soon as the data bundles were depleted and only worked once a new bundle was loaded. I have been double charged for data and would like this problem to be rectified as soon as possible as it is impossible to have spent such outstanding amounts on data despite constantly recharging. As a customer of more that 4 years at mtn who diligently pays every month , I will retract the contract and take my business elsewhere if it isn't rectified timeously.