Not true, of course!
I have a dim memory of Dr Crawley stating that if a child doesn't recover in six months then they can be rediagnosed with pervasive refusal syndrome. The child is then subjected to an intense course of vigorous physiotherapy with disastrous results as has happened under her jurisdiction. (I wish I could locate her quote.)
I've never seen that quote. But AYME released a leaflet saying most people recover from CFS in under 6 months. I was going to say I (or my child) have experienced the re diagnosis as PRS but that is not quite accurate (and was after 2 or more years). What Crawley did say was that the CFS diagnosis was correct and that she had cured that (with a leaflet, and colouring chart!) but now due to the stress of being ill my child had developed a disociative disorder. She later suggested to a local CAMHS consultant that she should diagnose PRS and that my child should be sent to a psych unit in London. So I suspect I am the source of the PRS stories but I was warned before hand (not sure by who) and so I think it has happened to others.