Just so people aren't worried, got another email from Nintendo saying there was an error and apologise and gave me a new code yesterday. Hopefully everyone should get theirs now.
I remember someone saying the code was too long. No it wasn't! It's 16 numbers. Less than 360 codes. I wonder how redeem codes will be used in the future...? Pre order dlc bonuses? That would be awesome! I always felt there hasn't been much reward for Pre ordering Nintendo games, but the games usually rule so it makes up for it.