Got put in low priority for afk in 1 game

i got ban for 5 game 20 min low prior for just 5 min afk in 1 game and I actually back to finish it. i know when i play i alway finish the game and not gone afk but right now i got ban for not being active in 1 game? is that how riot work?what happen to the game that I have finish with no afk?i need u to lift the ban on my account i'm not gonna spend 20 min waiting for 5 time for afk in 1 game