You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

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

ASSISTANT: Sure, I am here to help you with this. May I know your name please?

USER: Thank you. Susan Martinez.

ASSISTANT: Please wait for a mean while.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found as per your name to change it.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome.