Being charged more than I signed for

I app**** for a laptop contract with cell c, n they delivered it on the 28th of October, which i have to pay R429 a month the agent who helped me adviced me to call cell c before i use the data so that they set the limit to R430 of which i did cal them 2 days after and the consultant told me that i uses R42 more which means they will debit R430 plus R42. On the 31st of October they debited R348 because i got the laptop towards the end of October and did not recieved all the benefits which means they pro rated the account, and after they debited their money i did not recieve my monthly benefit and then i called them and they told me that my account is in areas of R2500, of which i dont understand how possible is that because there is no one who can use the data that cost R2500 in just two days, i called them last week to complain and they said they gonna get back to me with the full report of the websites i went to of which they did today but with no report, so they just wanna charge me rediculous amounts that i dont understand. So can you please help me on this matter