Billing provfile, bill to high

I have a data contract sim card with Telkom ever since august i have been paying more thanR1500 but my contract is supposed to be R159 and the other one is a top up sim card i am paying R200, my bill per moth is supposed to be R360. I bought the data sim for my little brother to use for his school work, but he always make calls with that data sim card and make the bill to be high so i called Telkom in August for them to decrease my spending limit to R50 but that did not happen, i called them again in September there said it was decreased , but still the in October my bill is sitting on an amount that is more than R1500,, i called the call center requested to speak to a supervisor the agent who assisted me said all team leaders and supervisors are busy on calls, i stayed on the line for more that one hour just to be told that the spending limit has now been decreased and agent said supervisors are busy there cannot talk to me i should just accept that he assisted me. i asked them to change my debit date to the 25th but there still debiting on the 2nd my account is now in errors I would like telkom to fix this problem i want my money back and wont be able to pay the money there saying i should pay because there agents are not s****ed to do there jobs properly