Taking my money and cutting my line

For the last month MTN has told me I need to pay money. I then paid the first R500 which they said I owed. Then a couple of days later you guys sent me an SMS saying I owed R500 and that my line would be cut. You then proceeded to cut my line. After dealing with your credit and customer care department, my line was re-opened. Then a few days later the same thing happened. Suddenly I had an overdrawn account for R999 when NOT ONCE DID ANYONE MENTION THIS, SO HOW DID THIS AMOUNT SUDDENLY COME ABOUT? I have not received a statement for MONTHS now, you can't just take my money. You guys have debited my account for R999.00 and I paid in another R500, which means you have R1499 of MY MONEY. I want an explanation for the R999 and why I was NEVER told about this before and I want the money that OWED TO ME BACK TODAY!!! Whoever manages your Social Media is ****, not once have I gotten a response from them. I will take Cell C's offer to buy me out of this contract. YOU'RE SERVICE HAS BEEN POOR AND I'M NOW ANGRY!