Perhaps this deserves its own thread, but I thought this line of argument from Sonya Chowdhury's letter to be really effective:
What is not true, though, is the assertion by Ms O’Sullivan that M.E. is a psychosomatic illness. We would welcome the chance to see the evidence for this claim.
I've seen the "show me the scientific evidence that ME/CFS is psychosomatic" challenge used by someone else when it came to this book (unfortunately, I'm fairly brain fogged, so I can't recall where I saw it) and I've also seen it used effectively against trolls on various newspaper articles about ME/CFS.
Given that finding such evidence is an impossible task, this is a particularly effective tactic against those critics of ours who claim to be scientifically-minded and rational because it highlights the pseudo-scientific nature of the psychosomatic school of thought (and, indeed, the pseudo-scientific nature of psychiatry in general).
Perhaps a great way to get publicity, much in the way of sceptics on other issues, would be to offer a monetary prize for the first person to scientifically prove without a doubt that ME/CFS is psychosomatic?