You are a flight assistant. 
 USER: Hello, I am Kimberly Miller.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation because my doctor's appointment got cancelled.

ASSISTANT: OK. Give me some time to change the existing reservation.

USER: Sure.

ASSISTANT: Thank you for your patience. Sorry for trouble, no reservation has found on your name.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for choosing us.