What do you mean by the email "they give doesn't work & not listed in subscriptions"? The subscriptions made with an in-app purchase that is managed by Apple are seen by viewing them with YOUR Apple account email address.
If you want to cancel a subscription from Apple - Apple Support
With that said, since you are being billed directly from Neocortex, that would indicate you signed up directly with the Developer and bypassed Apple's ability to manage the subscription. That would be done by navigating to their website where you would be charged whether you downloaded the app or not. Frequently a Social Media post will provide that link for you to sign up directly with the Developer. If you had used the in-app purchase after downloading the app instead, it would be managed by Apple and easily cancelled.
https://reface.ai/unboring/face-swap
Since you gave your account details directly to the Developer, then disputing the charge is your only option. Your bank must do more than just cancel your card and issue you a new one, they have to block future charges. The reason that is the case is that the PNO(Visa, Mastercard, etc) and your bank participate in the Automatic Billing Updater program that automatically transfers subscriptions to a new card. This is no surprise to your bank as they are fully aware how that works, but you will actually have to dispute the charge for that to happen.
You are still able to report the app to Apple using the reportaproblem.apple.com website, but it was not actually the app that was the problem, it was how you chose to make the purchase on their website instead. In the future stick with making in-app purchases managed by Apple.