This number called me today. It was Karina from the APX Apartments in Sydney making a courtesy call. She identified me by name when I rang.
My wife and daughter stayed there a few days ago, so all was above board.
So, it I quite possible others have actually stayed at one of their hotels.

I called back number (02) 8836 9196 spoke to a guy who said company name is APX.

Yes it is APX Apartments Sydney follow-up.

Legitimate call from the apartment building in which I stayed

I called back number (02) 8836 9196 spoke to a woman who said company name is APX.

I blocked this caller but I stayed at APX Apartments this week so I expect its a follow up. Thanks for Ian for the heads up.

calls after hours

I called back number (02) 8836 9196 rang once then goes to busy tone.