You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Angela Hernandez here.

ASSISTANT: How can I assist you at this moment?

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 can help you with that.

USER: Thank you.

ASSISTANT: Ok, please wait a moment.

USER: Take your time to check.

ASSISTANT: There is no previous reservation available in your name.

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

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

USER: Welcome.