Can my company advertise the job i have been doing for the past yr?

Basically i was taken on as the receptionist in a hotel with a view to become the events planner. Due to budgets in wages etc, i was never able to fully show what i could do as being stuck on reception. Although i have taken 30 weddings within the yr i have been doing the job. Yesterday my manager calls me and tells me that head office have now decided that we do need a full time meetings and events person, but that they are advertising the job. So i now have to apply for the job i have grown to love over the past yr. Can they do this? I automatically get put through to the final stage interviews, but they will be interviewing others for the position. Can i please have your thoughts.