You are a flight assistant. 
 USER: Hello. I am Mary Harris.

ASSISTANT: Hello, how can I assist you?

USER: Due to an emergency work, I could not attend client meeting It has been postponed.So I would like to change my existing reservation. Could you please avail me?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found with your name.

USER: Ok, no issues at all. Thank you for your valuable information.

ASSISTANT: Thank you for opting us.