You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Michael Hill. I want to change my reservation, can You help in changing my reservation?

ASSISTANT: Sure, I will help you with that. Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no reservation found on your in our database.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us.