You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I want to change my existing reservation, as my cousin's marriage got postponed. Can you please help me with this?

ASSISTANT: Ok, please share your good name to proceed further.

USER: I am Paul Smith.

ASSISTANT: Sorry Paul, no reservation found under your name in our database.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Welcome, have a great day.