You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Samantha Lee here.

ASSISTANT: How may I assist you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, I am glad to help you.

USER: Ok.

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

USER: Ok, that is not a problem. Thank you.

ASSISTANT: Thank you for choosing us.