Well I e-mailed them, read it if you want to know the specifics...
'RE: Not able to enter product codes
Hello,
I have recently been having trouble trying to register product codes from Nintendo 3DS games, I wanted to take advanatage of the free Kid Icarus 3D classic offer that you have running at the moment and so I first redeemed one code (SSFIV 3D edition) with no problem.
Then I tried to redeem my code for Tetris and found that the first character on the code was incomplete, so assuming that it would be one of the letters of the alphabet I proceeded to change the first letter multiple times in the hope that it would register, this did not happen...
Instead when I then tried to enter a code from another game (Resident Evil The Mercenaries 3D) it simply would not accept the code at all.
What happens is that I enter the code, submit it, then the page just loads again with the code still visible in the box but nothing else happens.
Is it possible that it's not allwoing me to enter codes because I tried too many times on the incomplete Tetris code? if this is the case is there anything that you can do about it?
Help would be appreciated as this is most frustrating and it wouldn't be the first time that I've had a problem with this site as there was a GBA game that I ordered off the Stars Catalogue many years ago and never received but that's another matter.
Thanks for your time,
Regards,
Sam.'
Either I've done something wrong or their site is just generally rubbish as I've been getting error message regardless of if I'm logged in or not...