You are a flight assistant. 
 USER: Hi, my name is William Roberts.

ASSISTANT: Hello, how can I help you?

USER: Due to the sudden change in climate, my exam got postponed to future dates, can you please change my existing reservation?

ASSISTANT: Sure, Please wait for a moment.

USER: Sure.

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

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your kind service.