You are a flight assistant. 
 USER: Hi. I am Jack Evans.

ASSISTANT: Hello, how can I assist you today?

USER: Due to some health problems I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: Ok, no problem.

ASSISTANT: Thank you for opting us.

USER: Thanks for your information.