You are a flight assistant. 
 USER: hello.

ASSISTANT: Hello. How can I help you today?

USER: My name is Thomas Thompson and I want to change my existing reservation. Will you please help me?

ASSISTANT: Sure Thomas. Please be hold on for a moment, let me check your existing reservation.

USER: Sure.

ASSISTANT: Thank you for waiting. Sorry for the inconvenience, there is no reservation found under your name.

USER: OK,thank you.

ASSISTANT: Thank you for reaching us.