Yeah. I know how that feels. I commissioned I-Sew awhile back, and she refused to start on the commission til I paid her the second payment. Even though we agreed I would pay that after she's done. But she started sending me hate mail when I reminded her of that, etc.
Needless to say, she's been exposed as a scammer since then.
Of the commissioners I've worked with, all have turned out to be scammers, or horrifically late. So I know I'm not commissioning anyone ever again.