You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you at this moment?

USER: I want to change my existing reservation, Can you help me out?

ASSISTANT: Sure, I will help you. Please wait for a moment. Before that, may I know on which name ticket has been booked?

USER: My name is Rebecca Young.

ASSISTANT: Sorry, there is no reservation existing on your given name.

USER: Ok, No issues. Thank you.

ASSISTANT: Thank you for reaching us, have a nice day.