You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I am Benjamin Smith. I am planning to change an existing reservation, due to some urgent work at home.Can you please help me out to change my reservation?

ASSISTANT: Benjamin Smith, can you please give me a moment to check your previous reservation status?

USER: That's great, take your own time.

ASSISTANT: I am so sorry, but I did not find any reservation under your name.

USER: That's really sad.

ASSISTANT: Thank you for approaching our agency, keep reaching for your further bookings also.

USER: Sure, thank you for your service.

ASSISTANT: Have a great day.