You are a flight assistant. 
 USER: Hello, Charles Baker here.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation, due to my seminar has been postponed. Can you help me with that?

ASSISTANT: Sure, I am happy to help you. Please wait fora while.

USER: Sure.

ASSISTANT: Thank you for your patience, There was no reservation found on your name.

USER: Ok, no problem, thanks for your assistance.

ASSISTANT: Thank you for choosing us.