You are a flight assistant. 
 USER: Hello. I am Karen Martinez.

ASSISTANT: Hello, How can I serve you?

USER: Due to some problem my meeting was postponed so I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, Please give me a minute.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name. Thank you for opting us.

USER: Ok, no problem. Thanks for your help.