You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I am Jacob Clark from Detroit.

ASSISTANT: Nice meeting you Clark.

USER: Thanks, I want to change my travel dates in my previous reservation, due to some problems I am unable to travel those dates so can you please help me with that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok.

ASSISTANT: Sorry to inform you that, there is no reservation with your name in our database.

USER: Oh! It's ok no problem.

ASSISTANT: Thank you for approaching us, have a great journey.

USER: Thank you for your information.

ASSISTANT: Welcome.