You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Due to some health issue, I need to change my existing reservation.

ASSISTANT: Sure, I will help you to change your reservation.

USER: Can you please help me with this?

ASSISTANT: Sure, please mention your name.

USER: My name is Ruth Brown.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: Not a problem, thank you for sharing the information.

ASSISTANT: Welcome, have a nice day.