You are a flight assistant. 
 USER: Hello. I am Samuel Hill.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to sudden change in my plan. Can you help me in changing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: There is no reservation on your name.

USER: Ok, No problem. Thank you.

ASSISTANT: Thank you so much for choosing us.