You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Thank you. I am Jack Parker.

ASSISTANT: Ok, please wait a minute I will get back to you.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry no reservation found on your name.

USER: Ok, no problem.

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

USER: Thank you.