You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Let me know your name to check for  the existing reservation.

USER: Sure, my name is Timothy Parker.

ASSISTANT: Hold on a minute.

USER: Sure.

ASSISTANT: Thank you for waiting, I did not find any reservation on your name to proceed for modification.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for availing us.