You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I give assistance to you?

USER: I want to change my existing reservation, due to my exams has been postponed.

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

ASSISTANT: May I know your name to trace your details?

USER: Sure, Ryan Jones is my name.

ASSISTANT: Thanks for your name, please wait.

USER: Sure.

ASSISTANT: Thanks for your patience, we are sorry to say that we did not find any reservation on your name to change.

USER: Ok, thanks for your service.

ASSISTANT: Thank you for availing us.