You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello,. How may I help you?

USER: I want to change my existing reservation due to my meeting got postponed. Can you assist me in changing my existing reservation?

ASSISTANT: Please let me know your name?

USER: Sure, Susan Martin is my name.

ASSISTANT: Ok. No reservation found.

USER: Ok, thank you.

ASSISTANT: Thanks.