You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you?

USER: Eric Walker here. I am planning to change my existing reservation, can you please help me?

ASSISTANT: sure, please wait for a while.

USER: Ok, take your time.

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

USER: That's ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your valuable information.