How to whiten greyed section of clothing

[Supertree]

My son’s p.e. kit is navy with white sections over the shoulders. It has today come out of the wash with the shoulders more grey than white. Is there any way of whitening this area?

[MikeUniformMike]

Colour run sheets?

[Fluffycloudland77]

Colour run remover and colour catches from now on in every wash.

[Supertree]

I had a colour catcher in there and it still ran. Any more ideas on how to whiten it again? Not sure the colour catchers will be able to reverse it now that it’s already happened.

[Fluffycloudland77]

Colour run removers different to colour catchers.