9 YEARS CLOSED BUT STILL OWEING

I have tried to get into contact with MTN LEGAL for the past 7 years now and no feedback. They then listed me at the time and was handed over to the lawyers, the account was then paid up and transfered back to MTN. I then called MTN and they advised that the account has been settled and is currently in a zero balance, I was requested to send MTN LEGAL and email advising them to close the account and update my ITC REcords, MTN LEGAL has never ever called me in 7 years, and now they telling me i owe them R4000, which i dispute! This is old debt more than 5 years and i am not LEGAL bound to pay this. I was advised it was settled, i had to get into contact with MTN as they never ever bothered to call me.\\ Can you please assist with this urgently. I had just about enough with MTN!!!!