phone number keeps calling, no one there and leaves no message

They called the house phone about 5 times now, always during business hours and leave a (recorded) message: "Hi, this is Carla blahblubb, this message is for blahblah, please call 312-604-7174". It'a a name I don't know and that sounds like a drunk person speaks it.
Caller ID says "Arnold Shar...", and calling the number is some law office with automated payment option in the menu.

they call us - we don't have a clue who they are.  we never answer cyz we don't know who they are.  but they leave messages.  first there's a voice saying hi, this is sheila pls call me.  i'm trying to reach...and then this "drunken" electronic voice comes on and, when it's understandable, it says something like rachel alvaredo.  well, there's no rachel anyone at our home!

They are a collection agency for either parking tickets or traffic tickets, which have not been paid.  The name of the law office is Arnold Scott Harris and they are based on downtown Chicago.

We get calls from this number, and others with a 414 area code number, that have the same recorded voice - identified as Sheila Carson - and either ask for a "Michael W. Smith", or other names that I can't understand.  They either say (the recorded message) that they are calling from Harris and Harris of Chicago, or Arnold S. Harris law firms.  The caller ID says either "Harris Harris" or Arnold Sharris.  They give different numbers to call back, including 312-604-7177 and 312-423-7484.  We have been getting calls every day for over two weeks.