Need help how this could happen!

Hello guys. Today the 29th of June 2016 I bought a RP Card in a Media Shop "Saturn".20€.I got home and tried to redeem the code. About 17:30 - 17:40.But it was redeemibg for like more than normal.In other words too long.So i restarted the game and tried to redeem it again but this time it said:Code has been already redeemed.I got no RP on my acc.I can guarantee that i was the only one (at least the only possible) to have tried to redeem the code. I have the reciept and everything.Please Riot take a look over my acc and my purchases.2 days ago i redeemed 10€ card without problems.Whats behind it?
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