Absa selling my info

ABSA is supplying my personal details to a collection agent DMC for a debt that has nothing to do with me. The only consistency is that I have the same surname as the debtor. 1. I have told both Absa & DMC on numerous occasions I am not the debtor. 2. I was told I should share details of all the people with similar name and should prove that I am not the said person? 3. Supplying private information is in contravention of POPI Act? But I was informed the onslaught would not stop from DMC & I could be held liable if I did not share the said information? ABSA also contacted me with another story of their info was *******ed & trying to reach said debtor/s. But they could not supply more info unless I supp**** the info? However I find it extremely odd that despite POPI companies like ABSA and DMC are a law unto themselves.