Company Is Trying To Force Me To Work An 8 Hour Shift Without Paying Me As A W2 Employee

So first off, some background. I am a service provider for a large company. I get paid based on the clients I have, If I have no clients I don’t get paid even if i’m clocked in and in the building. Some days I get only $20 for the one client I had that day.

Typically, I should be there from 10AM-6PM, but most cases where I only have one client at 5PM I will tell my manager that I will not come in until 3PM or so because I can’t afford to sit around for 6 hours for a client at the end of the day. When I do that she gets kind of upset and says I shouldn’t do that because we could get walk-in clients (very uncommon), but frankly I don’t care if i’m not getting paid (when i started they did not tell me it was going to be like this, they also lied about my base pay- saying i would get one even though i don’t.)

Anyways, today she showed me a paper I needed to sign, basically to my knowledge it would lock me into the schedule I currently have Two days a week 10AM-6PM for six months. Meaning that I could risk getting written up possibly if I don’t come in at those scheduled hours even though I would be sitting around unpaid.

I want to refuse to sign the paper unless it states i’m allowed to come and go based on whatever clients I have, I’m fine with the days I work, but I can’t sit around for hours unpaid. What they’re doing is illegal not paying me for these hours I work, I’ve been fighting back at it but I also don’t want to lose this job.

If I refuse to sign the paper, because it is illegal and violates my rights as a W2 employee (unless they want to start paying me…) Can they potentially fire me? And could I retaliate and make a case for wrongful termination? i’ve already reported the business to board of labor before (they didn’t do anything)

Thank you in advance!

Edit: I know I should quit, but jobs aren’t really booming in this field so I’m seeing how far I can take my retaliation without getting fired first.

Edit Edit: This is in Massachusetts and I am an esthetician, I make commission per service ($20) and tips, but they want me there at all hours of the work day without pay