You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Joseph Evans.

ASSISTANT: How can I assist you today?

USER: Can you please change my existing reservation as my plan to attend for film festival got postponed?

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Ok, take your time.

ASSISTANT: Joseph Evans, there is no reservation found under your name.

USER: It's ok, no problem. Thank you for your response.

ASSISTANT: You are welcome. Thank you for reaching us.