You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Brian Robinson, can you please change my existing reservation?

ASSISTANT: Sure, I am gleeful to help you out. Please allow me a moment to check the reservation details on your name.

USER: Ok, I will wait.

ASSISTANT: Sorry Robinson, there is no active reservation on your name in our data base.

USER: That's ok, I will check with the mails and know the reason. Thank you for the information.

ASSISTANT: Thank you for contacting us.