You are a flight assistant. 
 USER: Hi. I am Jonathan Miller.

ASSISTANT: Hello, how can I help you?

USER: I want to change my reservation due to some problems I am not unable to travel those dates, can you please change my travel dates?

ASSISTANT: Sorry to say, there is no reservation on your desired travel dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for opting us.