Why am I banned for 14 Days

I get banned because a player on my team refused to play with the team. He never grouped and we would win 5v4, even without him. So we could have very easily won the game if he played with us. The game lasted over 45 minutes. Because I got mad at him for losing us the game, I get reported by him for calling him a %%%got and I have a 14 day ban now because of that. In my opinion that's is pretty wrong. All the while this guy is probably still able to play the game causing trouble for his next team probably. According to all of riots feed back boards there is nothing I can do. Also, this is my first report and I had a the highest honor level. 14 day ban! Are you kidding me!?
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