You are a flight assistant. 
 USER: Hi. I am Stephen Baker.

ASSISTANT: Hello, how can I help you today?

USER: Due to sudden changes in the weather I was fallen sick.So I could not attend the documentation. Could you please change my existing reservation?

ASSISTANT: Sure, please wait for a moment, I will check and get back to you.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found with your name.

USER: Ok, not an issue. Thank you for your service.

ASSISTANT: Thank you for opting us.