There seems to be a slight issue with iOS7+ which causes a calendar syncing problem where the phone randomly syncs different calendar events. I’ve seen this mainly on the iPhone 6 but has also happened on the 5S
****Before continuing make sure you have the server details to recreate the account****
To fix this you’ll firstly need to remove the entire exchange active sync account from the iPhone.
To do this you’ll need
Click on “Settings”
Then Click on “Mail, Contacts, Calendars”
Then Select your Exchange account and click Delete Account at the bottom of the page
Now that’s deleted the connection with Exchange will be broken. We need to make a new Exchange partnership so we will need to remove the previous connection from Exchange too.
In the Exchange Management Console (EMC)
Go to Recipient Configuration –> Mailbox –> Highlight the user who is having the issues.
On the right you will see the screen below, select “Manage Mobile Phone”
Now you will see the iPhone in there so select it and then click remove.
If the EMC gives you an error saying that the remote device cannot be found you will need to go to the Exchange Management Shell and type in the following commands
Get-ActiveSyncDeviceStatistics -Mailbox [email protected]
This will produce an output. On there you will see a “guid” right click and select “mark” then highlight and right click.
The paste in this command;
Remove-ActiveSyncDevice -Id paste your guid here
Now that is completed exit out and then refresh the Manage Mobile Phone screen and you’ll see that the phone is gone.
Now follow this guide below to recreate the account on the iPhone