You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Nicholas Lee.

ASSISTANT: How may I assist you to day Lee?

USER: Due to sudden change in my planned dates of journey, I would like to change my reservation. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please hold on a moment.

USER: Ok, I will wait.

ASSISTANT: We regret to inform you that, there is no reservation on your name in our records.

USER: Not an issue with that one, thank you for your search and information.

ASSISTANT: Thank you for reaching us, have a great day.

USER: Welcome.