I disagree with only giving back 1500 zen from the 7500 Zen Pack. Many of the pack items have dragonborn specific stuff or if dragonborn you get X more. I think a refund of the entire thing was in order until it's fixed, the race is no good to my existing lvl 60's if I can't re-roll the race.
It doesn't turn off per the PC forums, you still loose the next # of XP and you don't get 3X XP. So you end up loosing portions of the double XP during the event basically. Just what I've read, use it was a warning and make sure. Like I said, might be ALT day.
I read several posts on the PC version that it does not stack and at the same time still reduces how much more XP bonus you get. I'd test it out and make sure before spending to much time on that character. Might just be a great weekend to start leveling an ALT that you didn't boost.