"He is now on the waiting list again"

My son with underlying issues had to go for day surgery here in January, we booked in before 7am, and waited in the reception. No one kept us up to date on what was going on all this time, Over 5 hours later he had become so unwell we had to leave. He is now on the waiting list again. And has been told he may have to go through this all for a second time. I would love someone to explain to me why if your op is expected to be afternoon why we were there at 7am. I am so hoping he gets the help needed next time.