You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I need to change my current reservation due to sudden change in my trip. Can you assist me?

ASSISTANT: May I know your name?

USER: Jacob Johnson.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

USER: No problem, thank you for helping.

ASSISTANT: Thank you.