You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, may I know your name?

USER: My name is Angela Brown.

ASSISTANT: Please give me a moment to check your ticket status.

USER: Sure,I will wait for your response.

ASSISTANT: Sorry Angela Brown, no reservation is available by your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.