You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Due to the inconvenience of  travel dates, I want to change my existing reservation. Can you please help me in changing my reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, myself Barbara Lopez.

ASSISTANT: Barbara Lopez, we couldn't find any reservation under your name in our database.

USER: That's ok no problem, it might be changed by my manager, but he didn't inform me.

ASSISTANT: Thank you for reaching us.

USER: Anyway, thank you for searching.