You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I can help you. Please let me know your name for checking your reservation status.

USER: Barbara Gonzalez here.

ASSISTANT: Thank you. Please wait, I will check and let you know.

USER: Sure.

ASSISTANT: I am sorry to inform you, there is no reservation found under your name in our database.

USER: No issues, thank you.

ASSISTANT: You are welcome and thank you for choosing us.