my board is being attacked HARD by a group of spammers

I have a made a new group called 'Staff' where i promoted a few users, and gave the group moderator privileges.

I have made a second group, called BANNED USERS, with no privileges at all, where banned users will be moved.

My mods (in group Staff) can access to the page where you edit user's infos, they can select a new Primary Group but when they click on submit the changes won't take effect.

For me, in my AdminCP, it works fine.

HELP PLZ!... or suggest me a better way of banning...

also, is there a way i can allow my moderators to ban IP address? I think you can only do it from the "Subscibtion" page in acp's OPTIONS.... is there a way i can allow mods to have access only to that page???