Hi Hermann, thank you for your post. First of all: the support is for free, only premium support (weekends and holidays,…) is a paid service.
Creating a child theme with a plugin is not working, breaks whole site.
How should this be done?
If a plugin is not working then there is a problem with the plugin, not with the theme. We always recommend creating the child-theme manually, because there are always problems with plugins or automatically generated child-themes (wrong stylesheet order, problems with the files in the header,…). There are a lot of tutorials out there where you can create a child-theme without a plugin.
For the WooCommerce problems: can you send us (info @ 7theme . net) a link to the page with the problems, then we can take a look at it. It’s hard to say what went wrong without seeing the problem and the source code.