Harassment

I am being harrassed by this company. I have been receiving calls for someone that I have not seen or spoken to in over 5 years. I have explained that I no longer have this persons contact details and would not know where they could find them but still the calls persisted. I then decided one day whilst at work to call them and advise them that they need to stop and remove my details from this persons profile. Since then I have been receiving calls daily on my work landline without my explicit permission. I feel harrassed at work, if i get a call from them on my cell and I am not able to answer they call my direct line at work. Today I received a call again and requested the girls name (Zimkhitha) and managers name (Andrew) so that i can understand why this keeps on happening. I was advised that the manager is in a meeting and that I should call later. Zimkhitha gave me the number however it takes me back to the call centre and not to Andrews number.