You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Gary Hill here.

ASSISTANT: How can I aid you today?

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

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Sorry, there is no reservation found on your name in our database.

USER: Oh! I think the ticket was not booked due to server issue. Anyway, thank you for the information.

ASSISTANT: Thanks for helping me.

USER: Welcome.