You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?\.

USER:  I am David Mitchell want to change my reservation due to heavy snow fall. Can you help me in changing?

ASSISTANT: Sure, I am here to help you. Please hold on.

USER: Ok.

ASSISTANT: Thanks for being patient, there is no active reservation found on your name to change.

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Thank you for availing us.