You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am George Hill.

ASSISTANT: How can I assist you?

USER: Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Ok Hill, please wait for a minute. Hill, there is no reservation found with your details.

USER: Sure,. That's fine.

ASSISTANT: Thank you for contacting us.

USER: Thank you for service.