I have not heard of them, but I don’t think they are associated with the famous Face Spa in Hong Kong, at least there is nothing on Face’s website about a Hong Kong branch (see
http://www.facebars.com/). There are many good spas in Hong Kong however. On the Kowloon side there is a very good spa in the Peninsula. You might also try the Intercontinental on the Kowloon side which I have not been to in some years, but was very good then, I have no reason to believe that has changed. I would imagine that the Kowloon Shangri-La has a spa. On the Hong Kong side, the Four Seasons, the Mandarin, the Grand Hyatt and the Mandarin Landmark all have very good spas, and you don’t have to be a guest to stay there. Check the hotel websites for information. With all of these spas, you can use their steam rooms, showers etc and often can use the gym and pools for the day as well (ask about the pool privileges does not always apply).
I would also say that right IN your hotel is an outlet of Pure, which may offer spa treatments, I would check this first. See
http://www.pure-fit.com/for all their locations.
For independent spas, I don’t know many on the Kowloon side. On the Hong Kong side, The Firm up in Hollywood Road area would be a good choice, a lively place, good treatments, and you can then lunch (dim sum at Dragon-I), and then antique and boutique in Soho (see
http://www.thefirm.com.hk/, ask about their most infamous client, Nancy Kissel). Pauaspa by Frederique is well-kown and Freerique has been in business in Hong Kong for more than 20 years,
http://www.pauaspa.com/. I also like Ellespa, see
http://www.ellespa.com/home.php, but that is in Repluse Bay, which may not be a convenient locatin, but is easy to do as part of a trip to Stanely, stop off before or after some shopping/lunch in Stanely. Or have brunch at the Verandah and then a treatment at the spa.