You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Shirley Walker, want to change an existing reservation due to some personal problem. Please help me out with that.

ASSISTANT: Sure, please wait a minute.

USER: Ok.

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

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

ASSISTANT: Most welcome.