As I mentioned, but didn't explain: There is online software that you can download to your computer to "rescue" them. Apparently it accesses the file system to get them. He said he knew it had them because the software showed him some of the messages and demanded a fee to restore them. He recognized them.

Mostly, clearing space simply amounts to setting a flag that space is available and it doesn't actually clear stuff. That's what 'shredders' do (as well as overwrite, etc.).