You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Andrew Thomas.

ASSISTANT: How may I guide you today?

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

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.