You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Thomas Lee from Austin. I want to change my travel dates, due to some problems I am unable to travel those dates so can you please change my reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found basis on your details.

USER: Oh! It's ok no problem. Thank you for your information.

ASSISTANT: Most welcome.