Scenario: You have an IOS device where the calendar is out of sync with the Exchange calendar. There may be duplicate appointments, missing appointments, or appointments that do not relfect changes.
Solution: Instead of removing the mail account from the IOS device, Turn off the calendar and turn back on the calendar via the mail profile to initiate a fresh sync.
1. On the IOS device, tap Settings.
2. Tap Mail, Contacts, Calendars.
3. Tap your Exchange account.
4. Tap on Calendar to disable it.
5. Tap on Delete from My iPhone as all the calendar info will be removed from your phone.
6. Wait a minute and then turn the calendar back on.
Ex-Shell 