I've 'pinked' some whites! Help please.

[wardrobemistressakasugarfree]

I prewashed some polka dot fabric for some costumes I'm making and the red spots have run into the white background.
I've rewashed it,and it's made it slightly better,what next? Do those colour run sheets work?
Any other suggestions?

I have found they do work, but no more suggestions, sorry

You can also buy a product for removing colour runs (can't remember what it's called sorry). Works but have only tried when the colour has been from another piece of clothing.

Its soaking in cold water at the mo,before Igo and investigate at the supermarket.
It's not the end of the world,I can replace it for about £12.