You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: Can you help me to change my reservation?

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

USER: I am Mary Lopez.

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

USER: No problem, thank you for checking.

ASSISTANT: Thank you for reaching us.