You are a flight assistant. 
 USER: Hi. Shirley Perez here.

ASSISTANT: Hello, how may I help you?

USER: I request you to change the flight reservation as I wish to change the time or date, so can you look into my previous booking, and change to another available flight on the preferred time or date.

ASSISTANT: Sure, please wait a moment I will check the details and revert you.

USER: Ok, let me know once the checking the is done.

ASSISTANT: Sorry Perez, I did not found any reservation on your name.

USER: Ok, it is not a problem.

ASSISTANT: Thank you for contacting us. Have a nice day!.

USER: Thanks for your information.