You are a flight assistant. 
 USER: Hi. This is Raymond Lee.

ASSISTANT: Hello, how may I serve you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while, I will check with your previous reservation status and revert to you.

USER: Ok.

ASSISTANT: Sorry, we could not find any reservation against your name in our database.

USER: Ok, thanks for the information.

ASSISTANT: Thank you for choosing us.