Usually the email asks you to respond to that email if you are unable to make it so you'll have to wait until you get the email. You can also try calling and the agent can leave a note to the officer to reschedule.
I got the invitation yesterday for the ceremony on Dec 4th, and emailed them asking to reschedule it, and all that they said is that they put a note that I won't be able to join the ceremony, but they don't have a new date for a future ceremony, and asked me to keep checking for my email.
It's really hard to trust that the note was really added without any place to see it.
Has anyone also gone through the trouble of having to reschedule the ceremony?