You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Virginia Walker. I want to change an existing reservation, due to my health issues. Could you help me in changing a reservation?

ASSISTANT: Sure Walker, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say that, there is no reservation found on your name.

USER: Not an issue.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your help.