You are a flight assistant. 
 USER: Hi, I am Rebecca Evans.

ASSISTANT: Hello, How can I assist you today?

USER: As my appointment with doctor got postponed I want to reschedule my reservation, can you help me in changing my existing reservation?

ASSISTANT: Sure, we are here to sort out with any help you need. I will check with list and let you know.

USER: Ok.

ASSISTANT: I have gone through all the reservation stored in our data base, but no flight is reserved with your name.

USER: Thank you for the response.

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