You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. What kind of assistance are you looking for?

USER:  I am Mark Thomas want to change my reservation due to prepone of my trip with friends. Can you help me in changing?

ASSISTANT: Sure, please hold on. I will get back to you with the current status.

USER: Ok.

ASSISTANT: Thanks for holding on, there is no reservation found on your name.

USER: Ok, thank you for your help.

ASSISTANT: Thanks for approaching us.