You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Margaret Davis. I need to change my existing reservation, can you help me in doing that?

ASSISTANT: Sure, I am here to help you in that. Please give me a moment to check your previous reservation status.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found on your name in our records.

USER: Thank you for the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.