On balance, my iPhone developed a problem with the screen whereby the touchscreen would work even though I wasn't touching it.
I knew I would be down in London a couple of days later, so booked in an appointment at the Genius bar, and took the phone along. The shop was packed, and had a slightly smug feel to it, but I was still able to be seen at the alloted time.
The guy quickly examined it for liquid damage, he replicated the fault, then asked that I wait ten minutes so he could replace the screen.
Ten minutes!! Samsung, Nokia etc ask for ten days!!
Anyway, because I'd done my homework and booked an appointment, problem solved.
Oh, and mine was bought from CPW and not direct.