My only suggestion if the leave issue affects certain booked events ect is to speak to OPM's or even email T.M.
I understand that it is causing problems with certain people.
I am not defending the new leave system, but at least they are acting on it and being more flexible.
Dont forget even if it was still the old leave system, and you bid for leave to go to a festivel, wedding or what ever there was never any promise you bid would be sucessful.