You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide to day?

USER: Due to my ill health I cannot travel, could you help me in changing the existing reservation?

ASSISTANT: Can I have your name to check whether your reservation is existed or not?

USER: My previous reservation has done with the name of Steven Brown.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: May be my brother has changed on behalf of me before.

ASSISTANT: That's ok, thank you for approaching us.

USER: Ok, thank you for quick response.

ASSISTANT: You are welcome.