You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I assist you?

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: Sure, I can help you with that. Can I know your name?

USER: Sure, my name is James Walker.

ASSISTANT: James Walker, sorry to inform you their is no reservation under your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for checking.

ASSISTANT: Have a great day, keep reaching us in future.