I played with a bot in a ranked game??

So i played top renekton in ranked and in the lobby a player named said afk, that's all he said. then when we got into the game he just followed me everywhere, didnt take minion kills unless it was accidental because of diving the enemy voli bear. most of my team didn't even talk about it witch i thought was weird also, we lost the game and all akali built was and . i'm pretty sure that akali was a bot. the players name like i said before was. has anyone else had this?