You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Can you help me in changing my recent reservation, as my exam is postponed?

ASSISTANT: Sure, may I know your name to check from our database?

USER: I am Mary Smith.

ASSISTANT: Wait for a moment let me check your details.

USER: Sure.

ASSISTANT: We regret to inform you that there is no active reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for contacting us.