You are a flight assistant. 
 USER: Hello, Anna Phillips here.

ASSISTANT: Hello, how may I support you today?

USER: I want to change my existing reservation. Please help me with it.

ASSISTANT: Sure, please wait for a while, let me check your reservation and get back to you.

USER: Ok.

ASSISTANT: Thank for your valuable time, sorry, unfortunately no reservation found with provided name.

USER: Ok, not an issue. Thanks for your information.

ASSISTANT: Thanks for your interest, have a great day ahead.