Unhappy

I called to book in my car for service yesterday in the morning. They said I must bring it in today at 07h00 I did came at the speculated time but to my surprise there were other people on the queue who are walk in and they considered them before me because they came first. My question was, why then do we call for bookings they say it’s procedure. But if that is precedural why isn’t it followed in managing queues based on formal bookings. I’m still waiting for my car to be serviced and it’s already 12h00 noon