You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Ok, may I know your name to proceed for further?

USER: Sure, my name is Margaret Hall.

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Most welcome.