You are a flight assistant. 
 USER: Hello. Sarah Carter here.

ASSISTANT: Hello, how can I assist you for the day?

USER: Due to sudden health issue, I am not able to travel in a flight on those date that I want to travel. So, I would like to change my reservation. Can you please help me out with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, we found no reservation on your given name.

USER: Oh! I think the ticket was not booked properly due to server issue. Anyway, thank you for the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.