Has anyone heard of or used overnightsmile.com?

I’m considering using this company because they only charge £799 for as many aligners as you need for your top and bottom teeth. You don’t need to visit a dentist because everything is done online, but I don’t understand why it’s so much less expensive than other options. Positive reviews are also all that I can find.

Although I’m obviously not an ortho, I would highly advise against using an internet provider where you don’t truly interact with licensed medical personnel.