You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: I am Emily Walker. I want to change my reservation, can you help in change my reservation?

ASSISTANT: Sure, I am here to help you with this. Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry Walker, there is no reservation found under your name to change it.

USER: That's ok, thank you for your help.

ASSISTANT: You are welcome always.