You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Joseph Phillips.

ASSISTANT: Ok.

USER: Actually, there is small change in my journey. Can you help me to change my existing reservation?

ASSISTANT: Sure, please wait I will check the status of your previous reservation.

USER: Ok.

ASSISTANT: Sorry, no reservation found as per your details.

USER: Thank you for your help.

ASSISTANT: Thank you for approaching us.