It sounds like it's optional. I can understand why you'd want to leave a negative review, but it seems a little extreme to demand a refund when the old functionality is still there and presumably fairly simple to switch to. It still does exactly what you paid for.
Thank you! When I filled in this form, it said I can cancel a purchase within 14 days of making one. Is it the case with all apps that you can get a refund, no questions asked, within 14 days?