You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be of your service?

USER: Can you change my existing reservation as my plan to meet my client got postponed?

ASSISTANT: Sure, please wait I will check your existing reservation in the database and revert you.

USER: Ok.

ASSISTANT: May I know your name to check the reservation?

USER: Carolyn Martin is my name.

ASSISTANT: Ok. Sorry, there is no reservation on your name to change.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us, have a pleasant day.