You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I abet you?

USER: I just want to change my existing reservation under the name of Richard Clark. Can you help me in this?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Thank you for being on hold, We are sorry to inform you that there is no reservation found with your name.

USER: It's ok, not a problem. Thank you for your information.

ASSISTANT: Thank you for availing us.