MTN South Africa

I have been charged incorrectly on my contract. It’s close to 2 years and to date they have not fixed it. Between area managers, MTN stores, emails, call center, now in the collection department etc etc. Still waiting and every 2 days they da all me from collections asking for the money. Every time I explain the matter and they will escalate 🤬… I have been told I will not win this case … is there a lawyer out there that can win this case? I have proof in writing what they did wrong , but MTN simply doesn’t care. I have been their client since 1989.