My very first quilt did this - royal blue backing, bled through along all the quilting lines. I didn't know what to do at the time, and ended up using bleach (which did remove the bleed, but also faded the quilt of course).
Colour Catchers are hard to find outside the US (Not sure where you are located) but if you can find them they may be your best shot. Oxyclean did a pretty good job on my last dye disaster (indigo blue onto white - see a trend here?).