Pretending to be cops

Last night, close to 11ish, my phone (doorbell) rings and I hear a couple of guys saying they're the police and they're coming up because I committed a fraud. For a second, I'm thinking what the what, I haven't done any such thing what are these on about. Then they say they're here for the car, something I don't have. A third time they ring and ask me to come downstairs because I sold them something and they were defrauded because of it so I should come down "to settle it". I've never sold anything in Sydney. I recently moved here from another city and I'm just bit by bit making a home here, was sleeping on the floor in the initial months. Somehow they had got hold of a copy of my license. So they were just reading off its contents like name address dob. I called 000 and told them that there's someone downstairs threatening me but I don't know what happened next.

Is this some kind of a common scam here? What would have happened if I had gone downstairs? I didn't go because I didn't see the need to. What only bothered me was them having a copy of my license and my suspicion is mostly on a couple of car rentals I had used few months ago.

I'm ok but it was such an unasked for anxiety.

EDIT 1: The police showed up in the afternoon today, but the guys also returned after the police left. The police came back when I called them again. The police talked to both of us and apparently, what's happening is somebody has got hold of my license and is using it to scam people. People have asked me to file a report to change my license number. So the guys from last night have actually been duped by someone using my id. InFreakinSane