You are a flight assistant. 
 USER: Hello, Dennis Robinson here.

ASSISTANT: Hello, how can I help you at this moment?

USER: Owing to an emergency, I would like to postpone my journey. Can you please change my existing reservation?

ASSISTANT: Sure, I will help you with this. Please be on hold for a moment.

USER: Ok, take your time.

ASSISTANT: Dennis Robinson, there is no active reservation found under your name in our database.

USER: It' s ok, no issues. Thank you for the information.

ASSISTANT: Thank you for contacting us.