uncerfied about the billing of my account

when i upgraded my cell c contract , i took out samsung tablet which i will get 500 mb on it and will pay R199.00 , i called in their contact centre on the 02/10/2015 @09:51 and i was told that there is extra r78 some rands , didnt get the figure correct , my question was , cos im no longer on a 100 min and 100 sms and 100data , why do i have to be charged so much , i was called by a team leader/ manager which i didnt get the name correctly , he assured me that everything was being sorted and on my billing date they will take R199.00 as per agrrement , to my suprise i was billed an amount of <br> CELL C SP *** 253.99- 10/31<br> CELL C SP *** 253.99- 09/30 <br> CELL C SP *** 322.54- 08/31<br> <br> my account nbr is *** , im very much not satisfied with the service i have been given by the provider and i need every cent that has been taken to be reversed back to my account , because these is highly un acceptable, i need explanation or i will cancel the contract and info my fellow collegues and family members and friends the kind of service im being offered... to be contacted after 5pm <br>