Over Charged for Capped Data

i have been querying my billing on my account with MTN, on the 7th of January 2015, and they had told me that my contract had been suspended due to over use of data, however as per my agreement with MTN Mall @ carnival the data was not capped on a Contract i had taken out for a Laptop, as i was meant to get 500 MB per month, and when the data had depleted i would be able to top up, however i had then queried this with the branch on the 8th of January, as the call centre told me that my bill was going to cost me around R1500.00, in total i would pay around 1800 as i have another contract with them, please note that i have still not received proper feedback, as well as my Money, as i was told that i would not be billed for the over use of Data, Please note that i Require assistance from the customer car manager or Director only as i have sent 10 mails, and the best they can say is we will get back to you, i have sent mails to the customer care email address and still no Response Ref : [#***] &amp