You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help?

USER: I am Jennifer Miller. Can you please help me in changing my existing reservation?

ASSISTANT: Sure, please wait while I take out your reservation details from our database.

USER: Sure.

ASSISTANT: I am sorry to inform you that there is no reservation found on your name to change.

USER: Not a problem, thank you.

ASSISTANT: Thank you.