You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for today?

USER: I want to change my existing reservation, due to some health issues. Can you please help me with it?

ASSISTANT: I am happy to help you in changing your reservation.

USER: Thank you.

ASSISTANT: Can you please provide your name to check the reservation status?

USER: My name is Matthew Brown.

ASSISTANT: Sorry to say this Matthew Brown, there is no active reservation with your name in our booking list.

USER: Ok, not a problem.Anyways, thank you.

ASSISTANT: You are welcome, thank you for reaching us.