DD fell on her knees and marked a pair of cotton/linen like trousers. I've so far tried:
Oxy stain remover and normal (30 degree) wash
Put detergent (non bio) directly onto marks and soak in cold water.
Soak in Bicarb and cold water.
Nothing is shifting those marks and it'd be such a shame to get rid of them (couldn't even give to charity shop in current state). Any ideas?