You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you help me to change my reservation?

ASSISTANT: Sure, We are here to help you. Can I know your name?

USER: I am Joshua Collins.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT:  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for reaching us.