Oh, how awful! I've never tried it, but some women in a quilt group I attend have used something called Color Catcher -- I think that's the name of it. Apparently did a great job of fixing problems like yours. Also, Alex in one of her classrooms (one of the earlier ones, I think) had a problem like that and got something from her local quilt store, so you might look for that, or check with your local quilt store. Good luck! And please let us know what you try and what happens.