You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, I am glad to help you. Could I have your name please?

USER: My name is Joshua Edwards.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes further.

USER: Anyway, thanks for the information.

ASSISTANT: You are welcome, have a great day.