Charged over 300 for a R99 contract

I was called by one of the staff at mrpmobile, trying to sell a tablet to me, for the price of R99 per month, when my billed arrived it was R389 when i called and queried the amount they said it was additional stuff loaded on the tablet, which i did not agreed to and extra data! i asked the lady to sent me the conversation that i had with the sales rep, she said they didnt sent her they email her that i said i do accept, however i asked ther to remove all additional stuff that was added to the tablet to be removed since i didnt understand the cost. Now this month same story i recv a invoice for R179, i hardly use the tablet the charged over R350 where the normal amount as discussed was only R99.00 per month, if i do net get feedback soon, be sure that i will refer this matter to the ombudsman as soon as possible i canot afford to spent over R200 per month for something that i did not agree to