You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Dorothy Davis, can you help me for changing my existing reservation, because my semester exams was postponed?

ASSISTANT: Sure, I am here to help you. Please give me a moment to check your details.

USER: Ok, I will wait for your reply.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Oh! It's ok, no problem thank you for your services.

ASSISTANT: Thank you for choosing us, have a nice day.