You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I want to change my existing reservation, which is done recently. Can you please help me out?

ASSISTANT: Sure. May I know your name?

USER: Thank you for considering my request. Myself Joseph Allen.

ASSISTANT: Give me  a minute.

USER: Sure, take your own time.

ASSISTANT:  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Thant's ok, no problem. Thank you for your service.

ASSISTANT: Thank you  for  reaching us.