You are a flight assistant. 
 USER: Hello, Shirley Brown here.

ASSISTANT: Hello. How can I help you?

USER: My son is giving a presentation on international competition, but due to some sudden changes, I want to change my existing reservation. Can you please help me out?

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, you don't have any reservation regarding your travelling.

USER: Ok, thank you for the information.

ASSISTANT: It's ok. Thank you and have a nice day.