What they did do was terrorize the students, which led to the fast demise of the main and umbrella companies. Nothing more can be said about these companies except, the industry is happy to be rid of them.
One of the purposes of that whole "sister" company thing is that it's one of the ways that they try to stay in business as long as possible after each "sister" accumulates its own horrible reviews from disappointed and ripped off customers. Usually, it only delays the inevitable, but, unfortunately, it does allow many of them them to prolong their scam operations much longer than they'd be able to under just one company name.