Caller: Refused to answer. Insisted "Personal reasons

They called asking for a family members estranged drug addicted ex boyfriend. They pronounced his name wrong on purpose at first then corrected themselves. They asked about old addresses and asked me to confirm or give a new address. I refused. I asked about the reason for the call or a name. They just kept insisting "personal reasons" or "I can't tell you." They pushed for the name and contact details of my sister. I refused.

they wouldn’t tell me the company name or what their job entails at all. They couldn’t even send me an email because they said that it reveals too much information and I would learn the nature of their business. I don’t understand why the need is to be so secretive. But to me it smells like debt collectors.