You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I best assist you?

USER: Owing to an emergency, my planned trip to Yosemite adventure with friends has been postponed. So I want you to change my existing reservation?

ASSISTANT: Sure, that what I am here. May I know your good name please?

USER: Sure, I had a recent reservation with name Ronald White.

ASSISTANT: Thanks for providing you name, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that there is no reservation found on name Ronald White.

USER: Ok, no worries at all. Thanks for your assistance.

ASSISTANT: Thanks for opting us, have a great day.