Bad service and *****ing my money.

I have been ben with MTN for more than 10 year now, I am very disappointed, I just loaded airtime for R100. and I owe the airtime advance of R20 . but when I check my balance its R34. and there is nothing I can do. if I call there is no service at the moment. where than do we go for help, these multi corporate are greedy and no one is watching as customer no one can help us. and I am Nkosie my number is ***. I don't fear anyone.