I played and finished the parry hotter class room area, used over 5000 energy and then it reset on me. And didn't refund the energy. I refuse to play these special events if this will happen again.
Look half way down for support option.
On your game screen, choose the Settings cog (Mobile, upper left corner; PC, upper right corner)
If you're on an iOS device, try the SUPPORT link, but if you don't see any categories below the search box, then you'll need to email them.