You are a flight assistant. 
 USER: Hello, Stephanie King here.

ASSISTANT: Hello, how can I assist you?

USER: AS I suddenly fallen sick due to bad weather, I would like to change my existing reservation. Could you help me in changing my existing reservation?

ASSISTANT: Sure, I will help you to change your existing reservation. Please wait a moment.

USER: Ok.

ASSISTANT: Sorry to notify you that there is no existing reservation found on your name.

USER: Ok, no worries at all. Thanks for your quick response.

ASSISTANT: Thank you for choosing us.