You are a flight assistant. 
 USER: Hello, I am Joshua White.

ASSISTANT: Hello. How can I assist you today?

USER: I want to alter my reservation, due to postponement of concert to be held at the place where I wanted to visit, can you please take your some time for helping me?

ASSISTANT: Ok, please give me a moment.

USER: Sure.

ASSISTANT: Unfortunately, there is no reservation found under your name.

USER: That's fine, thank you for checking.