[Oz]

You have a reason to complain, yes maybe. But you're definately not seeing this problem from the business owners perspective. They have:
-A new business, which isn't completely in the black yet
-Human Resource Issues - staff turnover just increased with you leaving, and they know the manager isn't doing his job. What are their options? Get rid of the manager, and watch you walk out the door and then be 2 staff members down instead of one? I would try and deal with one problem at a time. Either try to reform/train the current manager and worry about the $9/h floor staff job later - because there is a million high school/college age kids who can fill the $9/h position adequately and learn your tasks - whereas finding someone to be a full time manager for average pay that actually DOES A GOOD JOB will prove much more difficult.

Their personal finances and other business dealings are just that - private. You have made some massive assumptoins and leaps with your above inferences - the money to finance that property could be from either of their salaries, a financial restructure, a death in the family - who knows? Not me and not you because that is private business!