Pathetic service from MTN

I renewed my contract in January 2017 and the salesperson from Eikestad Stellenbosch mall never uploaded the discount I am supposed to receive. Therefore I pay double the amount every month. My contract is R469, but I am paying over R930 up to R970 every month. I have been back to the store several times. Every time they tell me they have escalated the problem. I called the 808 customer care number several times and the same ‘I have escalated the problem- sentence’ had been repeated to me. I have received so many query numbers already, but still nothing has been done about this problem. At the beginning of this month I had to pay another R930. It is obvious that my problem has never ever been escalated anywhere and this problem will persist until I take the necessary steps against MTN.