Currently on holiday in greece and my girlfriend has been ill since day 1. we think it's sunstroke - what should we do? she won't go to hospital

Ideally: You should go, need to make sure she is well hydrated....and try and convince her..you did not state in what capacity she is I'll...what are symptoms or complaints.....

Hydration: Staying hydrated is key. You'll know by how often she pees, and what color it is. More clear, more hydrated. More dark yellow, more dehydrated (unless she's taking vitamins). Going to the hospital depends how bad off she is and what her symptoms are. You'll have to make the call. Hope this helps!