You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I would like to change my existing reservation due to my exams, can you help me in doing that?

ASSISTANT: Let me know your name.

USER: Rebecca Williams here.

ASSISTANT: Sorry, no reservation found by your name.

USER: Ok, no issues. Thank you for the information.

ASSISTANT: Thank you.