Harrassed for an account that is not mine

I have been getting consistent calls for a Isaac Ngubeni. Every time i ask them to remove my number from their database as they have the wrong person and number, they say sorry sir, kill the call and then just call back again. There seems to be no one that understands the concept of liable, takes responsibility for the call center actions, or in any way shape or form actually resolves issues. Next stop, the Ombudsman and the legal council. I have had enough of the harassment and I've been nice long enough.