You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am George Moore. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.