You are a flight assistant. 
 USER: Hi, my name is Mark White.

ASSISTANT: Hello, how can I help you?

USER: Owing to an emergency, my boxing match is preponed. Can you help me in changing my existing reservation?

ASSISTANT: Sure. We have not found any reservation on your name.

USER: Ok, no issues. Thanks for your valuable information.

ASSISTANT: Thanks for choosing us. Have a good day.