You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Ok, please allow me to check with your previous booking. Meanwhile, may I know your good name?

USER: Check the reservation under the name of Cynthia Hall.

ASSISTANT: There is no reservation found by your name.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for choosing us.