Swedes again

Sorry, another swede thread.
Mine have got curly and yellowing leaves.
I've looked inside the leaf and think I can see aphids, now, if I still had any malathion left I'd spray them with that but then I'd be stuck with what to use when I ran out.
I'm under the impression that it's a banned substance because all of us who used to use it have died, or something.

So, what is it and how do I get rid?

Is it too late to start some more, these were sown direct into the soil. Should I start some in modules?

I have really bad mealy aphids on my brassicas this year despite it not usually being a problem (flea beatle is normally my biggest issue!). I have been squishing them by hand and my cabbages and sprouts have now rallied but it is really affecting the wee swedes. It is certainly hard to get them off once they infest the newly forming baby leaves!