You are a flight assistant. 
 USER: Hello. I am Samuel Evans.

ASSISTANT: Hello. How may I assist you today?

USER: I need to change my existing reservation, as my exam got postponed. Please help me in changing?

ASSISTANT: Sure, I am blissful to help you.

USER: Thank you.

ASSISTANT: Please wait for a while I will check status and revert you.

USER: Ok.

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

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

ASSISTANT: Thank you for availing us.