You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, please share your good name?

USER: I am Margaret Hill.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your given name.

USER: Not a problem, thank you.

ASSISTANT: Thank you for choosing us.