You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I am planning to change an existing reservation,due to health issue. Can you please help me out?

ASSISTANT: Ok, I am here to help you with that. May I know your good name?

USER: Thank you. My name is Andrew Green.

ASSISTANT: Please wait for a minute.

USER: Sure.

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

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

ASSISTANT: Thank you for reaching us.