I have a 2004 US-spec sedan, so I don't know if the fuel flap spring is the same. If it is, it's a common trouble spot with a pretty easy fix. Can you open the flap if you cram a credit card into the gap between the door and the body and then work the release lever? If so, get a helper to work the lever while you observe the release latch at the filler. Let us know if you see it moving.