Something definitely off about these people!

I just got a call from these people, just like everyone else is mentioning about the R15000 free voucher for a survey I never completed. Apparently someone nominated me but they wouldn't tell me who. They kept insisting that I tell them wether I was single, married or in a relationship which was very odd for me. When I said I was single they insisted I tell them who I was coming with to pick up the voucher.. I mean why not send it via email? why not tell me who nominated me or my business? why insist on knowing my marital status? something just feels off.. They said I should come pick it up tomorrow at their centurion office but I'm not going there.