Well my replacement arrived, screen was lovely, creamy white and clear. Only problem is I can't actually connect it to Calibre. I get a Format Disc message. I phoned Kobo, and honestly I think I'm better trained than they are, tried a factory reset but even the kobo desktop won't recognise it so I've phoned Argos and asked for a replacement.
Third one, am I a gluten for punishment or just an optimist?