You are a flight assistant. 
 USER: Hello, I am David Smith.

ASSISTANT: Hello David Smith. How can I support you 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 wait for a while.

USER: Sure.

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

USER: Ok, thanks for the information.

ASSISTANT: Thanks for approaching us.