You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, thanks for connecting with us. How can I help you?

USER:  please help me in making some changes in existing reservation, due to my busy schedule on my previously planned dates.

ASSISTANT: Ok, please tell your name to check the details of your reservation?

USER: My name is Katherine Collins.

ASSISTANT: Have you done the reservation with your name?

USER: Yes.

ASSISTANT: Then sorry, there is no reservation is found by your name.

USER: That's so sad.

ASSISTANT: Thank you and have a nice day.

USER: Thank you for checking.