You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Samantha Nelson.

ASSISTANT: How can I assist you at this moment?

USER: Can you help me for changing my existing reservation, because I have some work in Houston only so I have to stay there right now?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment. Sorry Nelson, no reservation found under your name.

USER: Oh! It's ok, no problem thank you for your quick response.

ASSISTANT: Thank you for choosing us, have a great day.