You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: I am glad you have contacted us for the assistance. I will help you. Please help me with your name.

USER: Thank you. My name is Dorothy Robinson.

ASSISTANT: Please allow me a minute.

USER: Sure.

ASSISTANT: Thank you. Dorothy Robinson, I am sorry to say that there is no flight ticket booked on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us. Have a nice day!.