You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Dorthy Thomas.

ASSISTANT: How can I assist you?

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

ASSISTANT: Ok, please wait I will check and revert you in a moment.

USER: Sure.

ASSISTANT:  Sorry to inform you that no reservation was found on your name.

USER: Not a problem, thank you for the information.

ASSISTANT:  Thank you for availing us.