I'll look into this issue, however we do not actively check Staff activity in the way you describe, so it's possible there are inactive Staff members who we have not noticed. I have reviewed all Staff members and the overwhelming majority were recently active as far as I can tell. I am not willing to discuss the performance of specific TeenHelp volunteers further as it's not the concern of other members.
If you are concerned about specific individuals please submit a feedback form explaining the issues we'll look into them:
http://www.teenhelp.org/misc.php?do=form&fid=18
We are always accepting new Staff applications and there are a range of roles, including Chat roles, which are currently open to all members to apply for here:
http://www.teenhelp.org/volunteer/