You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi,. How Can I help you ?

USER: I want to change an existing reservation, could you please help me out?

ASSISTANT: Sure. May I know your details please.

USER: I am Rebecca Baker.

ASSISTANT: Just a second please .

USER: Sure.

ASSISTANT: I am sorry I cannot find your reservation .

USER: So sad. Anyway, thank you for helping me.

ASSISTANT: Thank you .