You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you at this moment?

USER: I need to change my existing reservation, can you please help me?

ASSISTANT: Sure, I am here to help you with this.

USER: Ok.

ASSISTANT: Can you please provide your name to check your reservation status?

USER: Myself David Roberts.

ASSISTANT: David Roberts, there is no active reservation found under your name in our database.

USER: That's ok, thank you for the information.

ASSISTANT: Thank you for contacting us.