You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I would like to change my flight reservation as my trip got postponed, can you please help me?

ASSISTANT: May I know your name?

USER: Lisa Rodriguez.

ASSISTANT: Ok, please wait.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, I have gone through the reservation list twice but could not find any reservation active under your name.

USER: Thank you for your time.

ASSISTANT: Welcome Lisa Rodriguez.