You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

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, may I know your name?

USER: Yes, you can call me as Kenneth Lopez.

ASSISTANT: Ok, please wait a moment I will check with it and revert you.

USER: Sure.

ASSISTANT: Sorry there is no existing reservation found in your name.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you, have a nice day.