Why is Apple store appointment are given if they can't serve you

The worst experience of my life at Apple store Rundle mall, Adelaide. I made an appointment for 1:00pm and went ro the store early at 12:40pm. when i asked them they told me to wait until 1:00pm to be served. when i went back to them at 1:00pm they gave me place to sit and wait. i waited for 20minutes. when i asked them how long it will take, they said its not sure how it will take and told me to wait more. when i told them can you keep my phone for service and i will come later when it is fixed. they told no they can't keep, if i have to give the phone for service i have to send it by post. i just lost my patience and left. it is ridiculous apple store service after they spend huge amount of money on store and useless people on job for service.