Fellowship issues are the responsibility of the Archmage and the Fellowship officers.
The obvious remedy is to boot the offender out of the Fellowship if they are, in fact, violating policy or have poor manners. If the other members of the Fellowship seem to think that it's OK, then you may want to look for a fellowship that's more appropriate for your social preferences.
Folks tend to have a pretty good social filter. Your responses also need to be calm and reasonable, so that it will be easy for everybody to tell who's the troublemaker.