You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you?

USER: Myself David Brown. Due to some urgent entrepreneurship meeting, I am going to change my recent reservation. Can you please help me?

ASSISTANT: Sure, I will help you with that.

USER: Ok, I will wait for your response.

ASSISTANT: Please give me a moment to check you previous reservation status. Sorry, there is no reservation found on your name in our database.

USER: Not a big problem, anyhow thank you very much for your service.

ASSISTANT: Thank you for approaching us.