Our working hours are 9 to 5…
So it should show, 9:00 to 10:00, 10:00 to 11:00 etc for appointments. But it is showing incorrectly…
9:30 to 10:30, 10:30 to 11:30
How to fix this issue?
Have you looked at the business hours in the Dashboard Account and Settings section? 
Yes. Those hours are correct but still 30 minute difference.
Its working fine automatically now.
Glad to hear it working as expected.