Skratchie, your best bet is to rewash the quilt in hot water with Synthrapol (using, of course, a washing machine that uses lots of water). Once you have a bleed it can take multiple washings with Synthrapol to remove it all, but it usually works pretty well.

How much red fabric do you have? Do you want to replace all the cut fabric and have enough?

If you only have what you have, and not an overmuch of that, then stop using the steam function on your iron. Use only dry heat, empty the iron and iron something else first to be sure of no water dripping. Then wash the finished quilt with the color catchers.