MTN South Africa disgusting service

I have queried with MTN and for someone to get back to me about my contract and the extra charges I was charged when I did my upgrade . Their sales department don’t explain anything properly ,you ask for the discuss on an upgrade to be put in writing and again that wasn’t done . I have sent emails ,I have called to speak to management no one calls back ,managers are always unavailable and in all honesty they are very quick to take your money and when you query the problem you get promised by call consultants that someone will call you and nothing. I find their service to be very poor and the way the treat clients is disgusting to say the least .