I need to ban someone who can change their IP but is @ host *.client.comcast.net.
Is there a way where i can add wildcards to the @host part of the ban so that NO ONE at this host can get in?
ANY help appreciated, this is very important.

yes, u can
ban USES wildcards
e.g.
/mode #channel +b *!*@*.client.comcast.net

/help $address

//mode # +b $address(<name>, 11)

>:D

are u talking to me ??

No.