I have played this card in the past and while it feels rewarding at the time it really doesn't get you anywhere IMO. The first thing I would do is to voice your complaints with your supervisor (is that the owner?). If that doesn't work, go to their supervisor. If that doesn't work, then let them know that you are leaving. Threatening to leave is never a good situation for you or the employer in my experience and probably means that you will not have a long future there. It is easier to see if they make it right, and if not then start looking for work elsewhere.