You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you now?

USER: My name is Justin Green, can you please help me to change my reservation?

ASSISTANT: Sure Justin Green, I will help you with that. Please wait a moment.

USER: Ok, take your time.

ASSISTANT: Sorry Justin Green, no reservation has found under your name to change.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for choosing us.