What is this please, and has it killed my bean and cucumber?

Too established an infection to recover from, I would carefully bag the plants to try to prevent disturbing the mites, and chuck the whole crop I'm afraid.

I tried to recover an infection that had gone that far and subsequently wished I had just binned the lot. Everything died anyway, and spread in the meantime ...

 

Can you not smoke them to death without killing the cues?
That looks like the cold frame u built onto your house? You could open it to the heavens and wash away their sins?