Okay, just phoned the store yet again. Now I have been told that the event is being move from tuesday(26th) to sunday(24th), but WE STILL DON'T KNOW WHAT THE EVENT IS.
My guess is that it is the R/S Challenge though because if you look at the event schedule at pokemon-tcg.com it will tell you that the event scheduled for the 26th is the R/S Challenge.