You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I want to chnage my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, we are here to help you. May I know your name please?

USER: Sure, my name is Betty Collins.

ASSISTANT: Sorry to inform you that there is no active reservation found on your given name.

USER: That's ok, thank you for checking.

ASSISTANT: Thanks for contacting us.