You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello.

USER: I am Lisa Gonzalez.

ASSISTANT: By what way may I aid you for the day?

USER: I need to change to existing reservation as my trip has been postponed.

ASSISTANT: Ok.

USER: Will you help me in changing my reservation?

ASSISTANT: Sure, I will help you in changing the reservation.

USER: Thank you.

ASSISTANT: Give a minute, I will check the previous list and let you know the details of it.

USER: Sure.

ASSISTANT: Thank you for waiting.

USER: Ok.

ASSISTANT: I did not get any name to change your reservation.

USER: Ok, thank you for information.

ASSISTANT: Thank you.