Retayne is a dye fixative, but you're supposed to use it before you wash the fabric for the first time.
https://www.dharmatrading.com/chemicals/retayne.html
Synthrapol doesn't make the bleeding stop, but it helps keep it from adhering to other things in the wash.
If you've already washed in hot water several times and it still bleeds, it's probably best to throw it away. You're lucky that it's a FQ, rather than yards and yards of fabric.