You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am William Thomas.

ASSISTANT: Ok.

USER: Due to my health problem I want to change my reservation, can you please help me that?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no reservation done in your name to change.

USER: Ok, no problem. Thanks for your kind help.

ASSISTANT: Thank you for availing us.