Can't you dye it all a shade of red somewhat similar to what you already have? You might have to bleach the blue out again before you can do that, though. I'm sure a salon could fix it though.

Also, I don't see why you can't just dye it all black! Black is a natural hair color, just because certain people know it's not *your* natural color doesn't mean it's unacceptable. Sheesh!