You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: David Edwards here.

ASSISTANT: How may I guide you at this moment?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

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

USER: Ok.

ASSISTANT: David Edwards, there is no active reservation found under your name in our database to change it.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for utilising our service.