In general, in any dispute about access to a forum the first thing you need to do is contact the administrator of the forum. Normally that will be the creator of a forum. A link to the creator's profile page appears at the bottom of any Nabble forum page. You will find a link to email them on their profile page.
In this case I see that "jdm" is the creator and an administrator, so that is the person to email.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.