You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Ashley Gonzalez here. I would like to change my existing reservation as my appointment with doctor got postponed. Can you help me update my reservation?

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: That's fine, thanks for your help and information.

ASSISTANT: Most welcome.