MTN ****** me of R84

I agreed to a contract whereby I received R100 plus 25 sms and a data bundle on a monthly basis from MTN. This was agreed to over the phone with MTN Connect Direct and began on the 13 May 2015.<br> All transpired as agreed until the month of December. I was only credited with R16. As per usual I was not able to speak to customer services as it just rings indefinitely, no one answers or I just got cut off. I approached MTN Galleria for an explanation and was told they do not have authority to fix problems they only provide contracts and sell phones. this attitude is typical of MTN they do not have time for customers but endless time to get you to sign a deal. I was eventually successful in getting through to the 808 number and I was told that they cannot credit me with the R100 because I have five months old air time. The contract deal is that I receive R100 per month for the next two years so how is it that suddenly my air time has accumulated it is now five months old and they can only give R16 credit. What difference does it make how I choose to use my air time the point is they are to provide me with the R100 that they owe me and now refuse to do so.<br> I want my R100 credit