You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: Jack Collins here. 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 out. Please allow me a moment to check the reservation on your name.

USER: Ok, I will wait.

ASSISTANT: Sorry  Jack Collins , there is no active reservation on your name in our database.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for reaching us.