If this were my client, I would suggest the following:
1) Stop deferring.
2) Look for a new job. This is not a facetious comment. If the company is stealing money from the DC plan, the rot goes deep. Sudden job loss is a serious possibility. Better a controlled exit than an unplanned one.
Suppose you went to work one day and a repo person is hauling away the company's printer because of overdue bills. That would be an alarm bell that the company is in trouble. Failure to contribute deferrals to the 401(k) is like that, but worse.
3) At some point, notify the DOL. As others have noted, the company is engaged in criminal conduct. The DOL should be able to restore your money, as long as it is possible to do so. If there is no money, the company owner may go to jail, but that will be cold comfort.