You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Robert Thomas.

ASSISTANT: How can I aid you today?

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

ASSISTANT: Sure, I am here to help you to change your reservation.

USER: Thank you.

ASSISTANT: Please allow me a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, I didn't find any reservation on your name in our database.

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

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Welcome.