You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I want to change an existing reservation. Can you help me with that?

ASSISTANT: Sure, may I please know your name?

USER: Yes, I am Ronald Hernandez.

ASSISTANT: I am very sorry to inform you that there is no existing reservation found on your name. Sorry for the inconvenience.

USER: Ok, No issue.

ASSISTANT: Thanks for contacting us.

USER: Thank you.