You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What kind of help you need from our agency?

USER: I have planned for the trip, but I am unable to catch the flight, so I want to change my travel dates, could you please help me in alter my reservation?

ASSISTANT: Sure, can I know your name please?

USER: My previous reservation is with name Betty King.

ASSISTANT: Sorry Betty, there is no reservation found on your name.

USER: It's ok, thank you for the information.

ASSISTANT: You are welcome.