You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

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

ASSISTANT: Sure, I am here to help you for this. May I know your name please?

USER: Myself Jacob Garcia.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry for inconvenience, no reservation is found under your name to change.

USER: That's ok, thank you.

ASSISTANT: Thank you very much for approaching our agency.