Promotional Code Bug?

I recently got a card with Arcade Corki and Dreadnova Gankplank which is bound to expire on 11.05.2017. Last night I entered the Corki code and it told me that Corki and Arcade Corki were claimed for my account. I jumped into a game, selected Corki, my skin was still locked. I went out and checked the champion, Arcade Corki was Locked. I tried and enter the code again and it said that "It was a problem ..." basically my code was already redeemed. I made a ticket for Riot Support but I got no response yet.

Does anyone else got into this problem before and can help me out? I swear the code wasn't used I got it from Comicon, someone from Riot Staff gave it to me and to others at the League of Legends stand. And I also telling the truth when I say that it told me that the Skin and Champion were claimed. If I knew about this ss that. I still have the Dreadnova Gankplank unused.