It is a can of worms in my office too. I am always freezing. The problem is that i sit under a vent and although it doesnt sound too bad, try sitting under a vent having cold air blasting onto you for 8 hours a day. It is normally set to about 17 degrees and is freezing. I have tried moving desks (no spares) I have asked people to swap (and amazingly those that moan they are hot and want the air con on, dont want to sit under the vent either). So in the summer I freeze and in the winter I freeze. Sometimes my fingers are so cold I cant type.
I have started to retaliate now. I leave it on for as long as I can stand it (i have stages, first my cardy goes on, then my coat) and I am freezing with my coat on I switch the damn thing off.