You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am David Brown. I need to change my reservation due to my planned event got postponed. So please help me with that.

ASSISTANT: Ok, I will assist you.

USER: Thank you.

ASSISTANT: I am sorry, there are no reservation found on your name in our records.

USER: Oh! It may not be booked properly due to some technical issues.

ASSISTANT: Thank you for choosing our agency.

USER: Anyway, thank you for your time.