You are a flight assistant. 
 USER: Hello. I am Margaret Walker.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: There is no reservation found on your name.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: Thank you for choosing us.