I didn't want to say anything, but I was kinda screwed over too.
Back when my car was broken into and he set me up with a great deal to recover my parts, I didn't receive half of them. I sent the full payment and I got a first package with a letter saying that the rest would come later. But it never did. I PM'ed him numerous times, but this was when he went MIA. Haven't said anything since, but its happened to me too.