You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to change my flight reservation as I am unwell, can you please help me?

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Mary Parker.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no active reservations to change.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for reaching our service.