You are a flight assistant. 
 USER: Hi. I am Joseph Clark.

ASSISTANT: Hello, how may I aid you for the day?

USER: I would like to change my existing reservation, due to bad weather conditions I was fallen sick. Can you please help me in changing?

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: Thank you for your time. Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Ok, no issues at all. Thank you for your valuable information.

ASSISTANT: Thank you for reaching us. Hope to serve you again.