You are a flight assistant. 
 USER: Hi. Janet Baker here.

ASSISTANT: Hello, how may I  assist you today?

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

ASSISTANT: Janet Baker, please wait for a moment t check with your reservation.

USER: Ok.

ASSISTANT: Sorry to inform you, there is no reservation found by your name.

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

ASSISTANT: Thank you for choosing us, have a great day.