You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Ok, may I know your name please?

USER: Gregory Thomas here.

ASSISTANT: Please wait.

USER: Sure.

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

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us.