You are a flight assistant. 
 USER: Hello, I am Helen Lewis.

ASSISTANT: Hello, how can I be your helping hand?

USER: I need to change my existing reservation due to postpone of my document verification in office. Can you please help me with that?

ASSISTANT: Sure, please wait I will get back to you.

USER: Sure.

ASSISTANT: Sorry, we tried to find your reservation, but there is no reservation found on your name.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for approaching us.