Overcharged on Monthly Contract Invoice - Unable to make calls. Zero airtime/voice, sms's or data received.

I have not been able to make calls for a month. I currently have over R100 airtime and am still getting "insufficient funds available" to make a call message. I have restarted my phone multiple times. Other SIM cards work on my phone.

I have been charged an additional R90 a month on my contract. I have not received any airtime, data, voice or SMS's. What is the additioanl R90 for?

This is ridiculous MTN! I expect a response.