You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you today?

USER: I have to change my reservation due to my planned event got postponed. So please help me with that.

ASSISTANT: Sure, I am here to help you to change it.

USER: Thank you.

ASSISTANT: Can I have your good name please?

USER:  Sure, please check the  reservation with my name Helen Hall.

ASSISTANT: Ok, please wait for a couple of minutes.

USER: Sure, take your time.

ASSISTANT: Sorry to say that, there was no reservation found on your name to change it.

USER: Oh! It  may not be booked properly. Anyway, thank you for your time.

ASSISTANT: Thank you for approaching our service.

USER: Most welcome.