You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Patrick Mitchell here. 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, please wait a while.

USER: Ok, take your time.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: Oh! Not an issue. Anyway, thank you for the information.

ASSISTANT: Thank you for opting us.

USER: Welcome.