You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you at this moment?

USER: I have to change my ticket reservation that I am unable to travel on the dates which I have booked on my name Lisa Brown, can you help me?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Sorry Lisa, there is no existing reservation under your name.

USER: Ok, no issues with that one, thank you for your help.

ASSISTANT: Most welcome.