Anonymous participant 710 yeah they don't bother answering any emails. Their requirements page on their website barely explains anything as well, and has no mention of originals/copies.
your printouts had the printed signature, right? My letter didn't have one (not even a printed one), and I suspect maybe that's why they denied it. Maybe they would've accepted it with a printed one. But then again, none of my other docs had signatures either (bank statements etc). And I specifically asked them if all submitted docs had to be original, and they said yes.