You are a flight assistant. 
 USER: Hi, I am Rebecca Lopez.

ASSISTANT: Hello, how can I help you?

USER: I just want to change my existing reservation as my tournament got postponed.

ASSISTANT: Sure, Rebecca Lopez, we are here to help you. Please wait for a couple of minutes.

USER: Sure,.

ASSISTANT: Thanks for your patience. Sorry, we did not find any existing reservation based on your name.

USER: OK, Thank you for your information.

ASSISTANT: Thanks for reaching us. Have a nice day.