Hello kebab.
You're always supposed to shoot the zombies, as well as the zombies are supposed to infect the human.
Therefore, teaming is almost never one sided, as in this case you should have shot the zombie blocking other zombies.
Or what do you think it looks like, when one way to reach you is being blocked by a zombie and you're not shooting the blocking zombie? - Teaming.
In case you want to complain, please apply an unban request.
You can find the application forms from the top right corner of the main page.
EDIT: I see you've done the unbanrequest, I'll get back to you.