You are a flight assistant. 
 USER: Hello, I am Samuel Green.

ASSISTANT: Hello, how can I assist you today?

USER: Due to an emergency meeting, My trip has been postponed. Can you please help me out in changing my existing reservation?

ASSISTANT: Sure, give me a second.

USER: OK.

ASSISTANT: Thanks for your patience. There is no reservation found on your name.

USER: OK, no problem. Thanks for the help.

ASSISTANT: Thank you for choosing us.