poor time keeping,

I book an appointment online for 2 December 1:30pm, on the 1st of December i was called to confirm my appointment. I went to bank city spec savers I got the at 1:25 which was 5 minutes earlier to my appointment time. i was assisted by a guy by the name of Nhlanhla 1:30 passed i told him that I'm on lunch and i should be back at work by 2pm , he responded saying their system was done for the day, i was like i book online though... i was manage to consult at 1:48 almost 20 minutes late, as a result i reported late at work i could even finish what i came for... worse part the optometrist told me that Nhlanhla was suppose to let me in as i had an appointment because the guy that was in was just a walk in, but he didnt take me serious he kept on smilling, im very angry because i had to sign a warning for late coming while i was on time.