Help! How to get out dark dye out of cotton print clothes

[Badgerqueen]

My MIL put a new black top into the machine with a white and lights wash (argh) and my girls very pretty blouses have come out that horrid grey/blue colour (they were previously white with a purple and blue printed pattern). Is there any way to get them back to white? They are currently soaking in Napisan, but doesn't seem to be working. Any ideas?

I use Dylon Colour Run - that usually manages to get the dye back out of things.

Thank you will have a go.