Who went and detonated the dam?

Suddenly I seem inundated with agony aunt letters. The latest one:

[Dear DovBear]
There's a garrulous young man in my shul who offends me with his constant chatter. During Kabbalat Shabbat, for instance, he'll walk around the shul engaging people in open conversation (unlike more respectable member of the congregation he does nothing to conceal his talking.) During musaf he stands in the back chatting away. Our gabbai ignores it. Our Rabbi sits with his back to the congregation so is unacquainted with the disturbance. (Needless to say, this man wears a hat and long coat, and imagines himself superior in every way to the more modern elements in the room.) Can anything be done?
[Seething in Shul]

Readers? Its your pitch.