You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Due to health issue, I want to change my existing reservation. Can you help me out?

ASSISTANT: Sure, I will help you. May I know your name to check reservation?

USER: Sure, my name is Eric Brown.

ASSISTANT: Sorry, I cannot find any reservation with your name in our database.

USER: That's ok, thank you.

ASSISTANT: Thanks for contacting us.