@paolo @onepict I think it's pretty clear they aren't interested in a solution. The trainer is used to Zoom. If they'd just said "due to the technical issues yesterday the next session will be held on Zoom. We're sorry about this and we're working with the BBB folks to resolve the issues" I'd understand, but the language in the email said that no FOSS or European software was suitable, unlike a "proven commercial solution" like Zoom.
It wasn't just what was said, but how it was said.