You are a flight assistant. 
 USER: Hello, I am Richard Lewis.

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

USER: I want to change my existing reservation, due to some health issue. Can you help me with that?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name in the database.

USER: Ok, no problem. Thanks for your help.

ASSISTANT: Thank you for opting us.