You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to some technical issues. Can you help me with that?

ASSISTANT: Sure, please wait a moment. To check your reservation may I know your name?

USER: I am Robert Evans.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you.