You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Please share your name to check with your status.

USER: Sure, I am Charles Edwards.

ASSISTANT: No reservation found at the moment in our database on your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for choosing us.