You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change an existing reservation, can you help me to change reservation?

ASSISTANT: Sure, can I know your name please?

USER: My name is Emily Young.

ASSISTANT: OK, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Emily, there is no reservation found under your name.

USER: It's OK.

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

USER: Thank you for helping me.