No service rendered but receive their payment

I renewed by contract with MTN at the end of July 2015. The renewal was a data plan only. I have not been able to log on to the internet with the new data plan nor could I log in (make use of) the internet with the last 3 months of my previous contract. I have called on numerous occasions trying to get this sorted but with no luck. All agents gave me numbers to call to speak to the technical department but I either don't connect with an agent or when i do they cant assist. If this is not dealt with by the end of this month I will be forced to place a stop on the debit order as I can not continue paying for a data plan and not use my laptop for its intended purpose. i have lost a total of 6 gigs of Data at the cost of R1000.00.