Collecting on Prescribed debt

This company is trying to collect money from a prescribed account which they bought. The account has not been paid ever since 18/06/2017. It is 6 years without paying this debt and I have never acknowledged any debt or been blacklisted. This is ******* and I going to report them and instruct my legal representative to take this matter to court, they even put me on credit bureaus. It is ******* in South Africa to collect a debt that has been prescribed.