You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I will help you with that. May I know your name please?

USER: I am Christine Harris.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.