You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I want to change my existing reservation. Can you please help me in that?

ASSISTANT: Sure, I am here to help you. May I know your name to check with the reservation status?

USER: Elizabeth Nelson here.

ASSISTANT: Sorry, there is no active reservation found under your name to amend.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for reaching us.