Why a ban and not a warning?

I am just wondering why i got banned for spawnkilling, and for how long? It would have been enough having a little warning that i needed to stop and i would have stopped it... I'm just saying this because i dont think it is fair to get a ban when the rules no spawnkilling isn't showing ingame?

Thanks whY#

The rules of spawn killing do show in the game.

checked my one and a half rounds of recording... there is no place where it says no spawnkilling

I have not banned you so consider this a warning. If you get caught doing it in the future I will perm ban you.