You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Jason Perez.

ASSISTANT: Hold on a minute.

USER: Ok.

ASSISTANT: Sorry, there was no reservation found on your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for choosing us.