You are a flight assistant. 
 USER: Hello, my name is Michael Robinson.

ASSISTANT: Hello Robinson, how may I assist you?

USER: I would like to stay for some more days with my friend in Denver, so I want to make some changes in my reservation, can you please help me?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Sorry Robinson, there is no reservation found as per your name to change your reservation which is there with the city name Denver.

USER: That's fine, thank you for the information.

ASSISTANT: You are welcome always.