You are a flight assistant. 
 USER: Hi. I am Jack Walker.

ASSISTANT: Hello,. How may I assist you today?

USER: I would like to change my reservation due to sudden change in my schedule. Please help me with it.

ASSISTANT: Sure, please wait for a while I will revert you with current status.

USER: Ok.

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

USER: Thank you.

ASSISTANT: Thank you for availing us.