chillies year 4 driving me mad

they all germinate as mother nature intended
then the seed leafs on some not all slowly curl over 

i have gently wetted the leafs with a diluted fairiry liquid as an atteptd on white fly

to no avail

any ideAS PLEASE

XXXXXXX

Maybe they are getting too cold at night.  Maybe?

Go careful on the watering too. I water mine from the bottom, only sparingly, so they take up some. You don't want them sitting in water when the temp drops overnight when the heating goes off in the house etc

I'm not saying that's what's happening in your case, I'm just saying it might 

As long as they're not too cold and not too wet they should recover

If you used sterilised compost they shouldn't be infested with aphids at the seedling stage
Can you actually see evidence?

Mine go into a heated propagator to ensure even temperature as it gets really cold at night

Could yours be suffering fluctuating temps? 

Do the chillis prefer to be transfered into pots rather than into say raised beds within my polytunnel?