Tanks insta leaving dungeons

Across roughly 200 Heroic dungeons, at least 30 of them have had a tank that instantly leaves the moment they load into the dungeon, leaving the rest of us there unable to run it, and also unable to leave the party with out a 30 minute cooldown. This started to pick up a lot recently, as well has tanks selling "tanking service" for heroic dungeons for 100-300 gold per run. I dont see this as a coincidence. Is there any way we could get either A) a steeper penalty for leaving the dungeon before the first boss, or within the first 5-10 minutes or B) the ability to leave the party with out a penalty if someone does leave the party within the first 5 minutes or before the first boss? Its quickly becoming a big issue and is wasting a lot of peoples times. Theyre trying to grief their ****ty business into existence, ruining the server along the way.