You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you?

USER: I want to change an existing reservation. Can you please help me out?

ASSISTANT: Sure, can you please tell me your name to check your existing reservation?

USER: Sure, my name is Emma Clark.

ASSISTANT: OK, please wait a moment. I will check for the existing reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found with your name.

USER: OK, thank you for your information.

ASSISTANT: Welcome. Thank you for reaching us. Have a good day.