I've got a 2nd OP3 sat in a shop, tried to cancel the order 3 times with O2 now
Leave it 7 days and they cancel the order anyway. I called into shop on Saturday to cancel mine which they duly did, though couldn't have any paperwork saying as much. Monday I got an email from O2 saying they were sorry that I'd not collected the phone and were now canceling as it had been 7 days. The O2 shop should have sent it back on Monday.
They may have canceled the order but not put money back in my account yet.