You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Matthew Perez.

ASSISTANT: How can I assist you?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I'm glad to help you with that. Please be on hold for few seconds.

USER: Ok.

ASSISTANT: Matthew Perez, there is no reservation found under your name in our database to do modifications in that.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us, have a great day.