When I had the rug business I would dye a lot of fabric. This sounds like they used the dye "turquoise" as it is one of the worst ones to get to quit bleeding. Actually sew a small ( 2 x 3 ) triangle of unbleached muslin in the corner and wash it again, with a handful of color catchers. Dry it in the hottest dryer you have. Then take the stitches out and see if the dye actually transferred. If it has, then the fabric needs to be returned to the store. You've done all you can. I just didn't want you to throw it out if the color catcher turned a color. Even if you wash a color catcher with no fabric, sometimes they turn shades just be being washed.