You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, may I know your name?

USER: Myself Robert Collins.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.