At least NOA was forgiving at times. Worked there one Christmas dealing with repairs, the Zelda bonus disc, and other stuff. Though, at same time I can understand why they do what they do sometimes. The shit folks try to pull over... but in this case, if it's their own doing think they should at least eat the cost. If nothing else say "This is it. Anything else will cost you on your own." The fact they're trying to charge you under warranty makes it even worse. God, I pray to the Pokemon gods above that my Charizard LL never has issues. *knocks on wood*
In any case, my verdict would be to pay it and move on. If nothing else, to get it back and fixed. Though at same time it could come back with another issue. Know a friend in America who has sent his in repeatedly because the issue they claimed to have fixed doesn't get fixed.