What can I do to stop this?

[Jpec07]

That really sucks, man. I've seen that happen a lot, and tanks especially are unpunished by it, because in 30 minutes they can just requeue and get in instantly. Usually if a tank does it, it's because they got an instance they really would rather not have to do (I've not done it here yet, but I may have been guilty a few times in WoW).

The best thing you can do is find a pocket tank, or a few. See if there's anyone in your FC who wants to chain dungeons with you, or ask in /shout. Or even make a party in party finder asking for a group to go with. If you take out the randomness of it, people are a lot less likely to bail without warning.