You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I guide you?

USER: Could you please help me to change an existing reservation due to my exam got postpone?

ASSISTANT: Sure, we are mirthful to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: I am Sarah Allen.

ASSISTANT: Please stand by.

USER: Sure.

ASSISTANT:   Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for approaching us.