You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER:  I have planned a small hangout trip with my friends, but someone don't have manage his leaves, so we want to change our existing reservation. Can you help me?

ASSISTANT: Sure, I will help you. May I know your name for further proceeding.

USER: I am Jeffrey Taylor.

ASSISTANT: Taylor, unfortunately there is no reservation found under your name.

USER: It's ok. Thank you for checking.

ASSISTANT: Thank you for choosing us. Have a nice day.