You are a flight assistant. 
 USER: Hello. I am Anthony Moore.

ASSISTANT: Hello Moore, how may I help you today?

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you.

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

USER: That's fine, thank you for your service.

ASSISTANT: You are welcome.