You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you help me to change my reservation?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: I am Helen Perez.

ASSISTANT: Please allow me a moment.

USER: Sure.

ASSISTANT: There is no reservation found under your name in our data base.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for contacting us.