You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: My name is Dorothy Thompson. I want to change my existing reservation due to my exams got postponed.

ASSISTANT: Ok, please hold on, let me check your existing reservation.

USER: Sure.

ASSISTANT: Thank you for holding on, we could not found any reservation to change on your provided name.

USER: Ok, No problem. Thanks for the information.

ASSISTANT: Thanks for contacting us.