You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello.

USER: I am Barbara Walker.

ASSISTANT: Please let us know, How exactly I can help you at my best today?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Sure, I can help you in that.

USER: Thank You.

ASSISTANT: Please hold on for a while.

USER: Sure.

ASSISTANT: Thanks for your time. Sorry Barbara Walker, there is no active reservation on your name to change it.

USER: Ok, thanks for your kind effort.

ASSISTANT: Thanks for approaching us.