You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Yes, I can help you. Sorry to inform you that there is no reservation found on your name.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for contacting us.

USER: Most welcome.