You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Angela Walker.

ASSISTANT: How can I help you?

USER: Due to some client meeting, I am going to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Sure, I will wait for your kind response.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: Not a big deal, anyway thank you very much for your kind service.

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.