It was a fraudster trying to confirm where you lived from what info they could get from ur ad and socialing telco companies and asking if the car was for sale to confirm they had the right info,. lock the car up.

Rang both my number and my son's. Nobody there when answered. Sent a text to number asking who it was. They replied "do you have a car for sale?" We do at present and asked which car. No reply. Assume it is some kind of scammer - my son's number was never listed in the advertisement which seems odd.