Towing Issues: towing questions, leasing office, tow company

Question
if my car has no tags on it because i have sold it and i am awaiting the new owner to come pick it up, it is towed (stating they believed it was abandoned) what are the requirements the tow company or leasing office are required to do before towing the car.  it is my car, i did sell it, i did already turn the tags in...but they towed the car without leaving any 24 hour notice saying they believed it to be abandoned.  how can they possibly know the car is abandoned if they have only seen the car once without tags?

Answer
You did not say where the car was towed from. Private property? A public street or highway? Basically no car can be on the street unless it is registered. Private property might be different, but towing without tags on private property is not my area of expertise.