You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I guide you?

USER: I am Carol Lewis. Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, I will help you. Can you please give me a minute to check the ticket status?

USER: Sure, take your own time.

ASSISTANT: Sorry Lewis, there is no reservation found with your name in our system database.

USER: That's fine. Thank you for your help.

ASSISTANT: Thank you for choosing us.