Is there any cheat that protects you from a voteban?

Because we just votebanned a cheater X on server X for cheating. He is still there.

No. But it can happen that the plugin needs a restart, or another plugin prevents the votekick from functioning :) 

^^ what he said 

'Out of the box' !voiteban addons are not necessarily functional the way you want them to be,, They can seem quite detailed to setup correctly.  

Suggestion:
 Read Every option one at a time, adjust correct, and then test it. (with a friend, not someone that will be randomly freaking out cause they are being voted out LOL! )     ;)