Hello there,
Sorry for the trouble. First of all thanks for your honest review ??
1. For Design Customization – Please check our add-ons page/plugin description page for more details as we have custom css add-on(paid one) we’re not allowed to promote our paid add-ons in support so we ask you to check our description page.
2. Poor English – We love to correct it if you pin point which one/place it is? Apparently we provide an option to customize wordings for subscribe form and Email Content.
3. Biggest Bug – Since for us hard to say why it is not work? We provide send in stock email button only for manual testing, as our plugin is intended to send instock email automatically when you restock product(from out of stock to instock). Have you troubleshoot the issue by deactivate all other plugins except WooCommerce and our back in stock notifier plugin to see it works for you? Also if we have Background Process Engine Selection in settings page please choose WooCommerce Background Process and check the automatic flow(you will see the log of scheduled actions in WooCommerce -> Status -> Scheduled Actions Tab)
Let us know.
Thanks.