You are a flight assistant. 
 USER: Hi, I am Amy Collins.

ASSISTANT: Hello, how can I assist you at this moment?

USER: Owing to an emergency, my planned trip to Yosemite adventure with friends got postponed. So I request you to change my existing reservation.

ASSISTANT: Sure Collins, I will help you. Please wait for a while because I need to check your present status.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation on name of Amy Collins.

USER: Ok, not an issue. Thank you for your help.

ASSISTANT: Thank you for opting us, have a nice day.