Hi Kev, I don't mean to patronise,but I'm a novice just starting out this year, I didn't let my birds out till they were dropping from there perches with me whistling and shaking the food tin. I let them out knowing that if I shook the tin and whistled they'd be back no problem, in the first few weeks of leeting them out I over fed them once and they wouldn't come back for anything, so I kept them lean until I started doing training flight with them. Now they come in at the shake of a tin even if they've ben fed, takes them a few minutes more but it works.
Could it be that they are fat, have you been putting food out for them? For a bird to spend three nights on the tiles and not be hungry is puzzling.
Hope this helps,
LNK