You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I serve you?

USER: I am Gregory Campbell, I want to change my reservation due to some health issue, can you please help me with it.

ASSISTANT: Sure, Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for opting us.