Got put in low priority for 5 min afk in 1 game

i got ban for 5 game 20 min low prior for just 5 min afk in 1 game that I actually back to finish. i know when i play i alway finish the game and not gone afk but right now i got put in low priority for not being to finish 1 game? is that how riot work?what happen to the game that I have finish without afk?i want my account lift from the low priority i'm not gonna spend 20 min for 5 time waiting for afk in 1 game