You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me to change my existing reservation, due to my trip has been postponed?

ASSISTANT: May I know your name?

USER: Nicole Hall is my name.

ASSISTANT: Ok, please allow me to check with availability of flights.

USER: Sure.

ASSISTANT: Nicole Hall, there is no active reservation by your  name.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us.