So anyone has experience doing standby on earlier flight for confirmed business class paid ticket?

I had "Z" inventory ticket for yesterday night bom-blr.. Reached airport early and Checkin staff said "seats are available sir, all biz class is empty" but we can't change your ticket as that inventory is not available.. Seriously? They still wait for that fare bucket even one hour before flight?? Called jet reservations and they said airport has to do it... Airport said we can't change unless reservations makes the change to ticket... Gave up finally and went and had two drinks...