Banned, but I've never played?!!

I've been banned from 5v5 ranked for no reason. I'm not sure whats happening. I tried to start but instantly banned.. I've never gave anyone hassle in ARAM or normal games. Its not like i've "voted" a ban.. its everytime i try to play a ranked game. Its giving me a 20 min wait just for it to fail again.... Is the new client broken? I pick a champ, then I get a 20min wait/ban for leaving game?
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