I've had it happen before.
For me, I saw their "final revision" and was not satisfied. I went back to the drawing board, providing a demo page of the layout I needed, and wanted that was more detail oriented than the first. I also left nothing up to them and their creativity. Everything from the colors, functionality, and even the font and size was provided.
It was a huge pain in the ass.
But for me it was, either do this as the example. Or you do not get paid your other half, and I go elsewhere. I gave them one chance to make it right. Even though they bitched about it "not being in the contract". After they bitched, and did what I asked. I paid them the other half, plus an additional 25% for their hastle.
They were happy clams.
So while I would never use them again ever. I prefer to give atleast ONE chance for them to fix the situation. They can bitch all they want, but they have the opportunity to be professional. However, I remove all creative "input" from them, and they no longer have any choice in how they like it, think it should be done, or whatever.
