You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Anna Williams, want to alter my reservation. Please help me.

ASSISTANT: Sure, I can help you.

USER: Thank you.

ASSISTANT: Please wait.

USER: Ok.

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

USER: That's ok, thank you.

ASSISTANT: Most welcome.