Anyone:
Correct me if I’m wrong but are the check in staff required to upgrade other pax if there are seats open and you are holding a J class ticket? I don’t know I rarely use the staff travel system.
If not, I suggest you talk to your Chief Pilot or Deputy (if they are approachable) or speak to someone in Operations. You have to go higher up the food chain if you want to get results.
Find out from your CP or Operations as who is in charge of the airport staff and then ask them to look into it.
Speaking to BN is like pi$$ing into the wind at best.
Should be taken further if the check in staff violated any rules. If not, it will continue to happen.