Best way to get LOTS of mud out of a white top?

[cherryboomboom]

Ds white P.E. t-shirt has come back from school absolutely plastered in mud (again). Can someone please tell me how to get it out?
I usually spray stain remover and leave for ages then put in wash with bio powder and vanish boost powder for whites. It never comes out, don't mind the odd stain as its only a P.E. top, but this will have to be chucked if it doesn't work this time.
Please can someone help me? I am starting to wonder if my washing machine is just plain rubbish!!

Is it worth bothering with, will it not just become full of mud next week? I'd wash it and send him back in it. Am I a bad Mother?

Usually I would do that so no, you are not a bad mother. But it is really bad this time (think more of a brown top with flecks of white) they were playing rugby on a field in the pooring rain!
And with the risk of sounding like a Daz advert, I want to know how to get my whites white

When DS played rugby we had this with the heavy old-fashioned cotton shorts (who picks these kits FFS?)

One boy was always immaculate and, after the rest of us trying scrubbing with a nail brush, Vanish, etc, we asked his mum how she did it. The answer was "soak them overnight in the bidet with a glug of Domestos then hot wash in the machine". Don't know how key having a bidet is though!

soak over night in water + scoop of bio powder.
then add a scoop of soda crystals when you wash the next day.

hang outside to some uv rays for additional bleach effect to dry.

Thank you will give it a go!