You are a flight assistant. 
 USER: Hello. I am Sarah Rodriguez.

ASSISTANT: Hello, how may I address you?

USER: I need to change my existing reservation, Can you help me for change reservation please?

ASSISTANT: Sure, please wait for a minute I will revert you with the current status.

USER: Sure.

ASSISTANT: Sorry to inform that there is no reservation found with your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing our service.