You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you out?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, I will help you in changing the ticket. May I know your name please?

USER: I am Catherine Jones.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us.