MTN FALSY BLACKLISTED ME!!

I was falsely backlisted by MTN due to non payment of which I have proof of payment,. Can anyone help me settle this because apparently nobody from MTN Somerset Mall or MTN Head office can help me. I need my name to be cleared as soon as possible. Also if their is a lawyer or company that can help me sue MTN south Africa for ***** and defamation of character. I have never hade a bad credit record in my life until useless MTN!