You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you today?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, may I know your name please for checking your reservation status?

USER: I have reserved my flight ticket in the name of katherine Campbell.

ASSISTANT: Ok Campbell, please be online for sometime.

USER: Ok, sure.

ASSISTANT: Sorry Campbell, I have not found any reservation by your name in our database.

USER: Ok, fine not an issue. Thank you for assisting me.\.

ASSISTANT: Thank you so much for contacting us and have a nice day.