You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I would like to change my dates of existing reservation as my holiday dates are changed by my boss, can you help me?

ASSISTANT: Sure, may I know your name please?

USER: Sure, myself George Johnson.

ASSISTANT: Sorry, there is no reservation with your name to change further.

USER: Oh! That's very sad news to hear from you. Anyways, thank you for checking.

ASSISTANT: Thank you for opting us.

USER: You are most welcome.