You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I best help you?

USER:  I am Susan Martin want to change my reservation due to prepone of my meeting. Can you help me in changing?

ASSISTANT: Sure, wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found with your name.

USER: Thank you for your help.

ASSISTANT: Thanks for opting us.