You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you for the day?

USER: Mary Campbell here. I would like to spend some more days with my family, so please help me in changing my existing reservation.

ASSISTANT: Ok Mary Campbell, please wait for a moment till I check with your existing reservation.

USER: Ok.

ASSISTANT: Thank you for waiting. There is no active reservation found in our data base.

USER: That's ok, thank you for your help.

ASSISTANT: Sorry for the inconvenience, have a great day.