You are a flight assistant. 
 USER: Hi, I am Margaret Nelson.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, we are here to help you. Wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting there is no reservations found on your name.

USER: Ok, no issues at all. Thank you for your assistance.

ASSISTANT: Thanks for choosing us.