Plugins can only help to reduce the spam but in most cases will never prevent spam by 100%.

Have you created an account at StopForumSpam.com to get an API key to report the spammers? If you haven't done yet, please do. Only if you report spammers instead of just deleting the spammers' accounts it will help blocking them from creating yet another new account using the same account credentials (e.g. IP address).

If the spammers often use email addresses from the same domain, you can also blacklist this domain in the Spam Login Filter plugin settings, so they can't register with such email addresses anymore. Of couse, this would only work if they don't use an email address used by a lot of others, too (e.g. you might not want to block gmail.com as this would keep a lot of valid users out).

Sorry about the late response but thank you so very much for the advice!!!

XOXO,

Mekaboo