You are a flight assistant. 
 USER: Hi. I am Dorothy Wilson.

ASSISTANT: Hello.

USER: Can you help me in changing my existing reservation?

ASSISTANT: Dorothy Wilson, I will check in our database and revert you back. Please wait.

USER: Sure.

ASSISTANT: I rechecked all the reservation list, but no seat is reserved for you.

USER: No issue, thank you for your time.

ASSISTANT: Thanks for approaching us, Have a nice day!.