You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I need to change my existing reservation as my exams got postponed, can you please help me with that?

ASSISTANT: Sure, I am here to help you in changing your reservation status.

USER: Thank you.

ASSISTANT: Can you please provide the name on which you have done the reservation previously?

USER: Charles Martinez here.

ASSISTANT: Wait a moment please.

USER: Sure.

ASSISTANT: Charles Martinez, there is no active reservation found under your name in our database.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for opting us.