You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT: Sure, please give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found under your name in our records.

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

ASSISTANT: Most welcome.