They are not from Hong Kong and I can tell you why, in all of Guangdong there is only one legit educational company from Hong Kong that is authorized by the provincial board of education to operate, and this is not Shenzhen-Hongkong International Education Center.

Probably a crap Chinese company pretending to be from HK. Ask them for their HK business licence. You can also call the HK main Art Center in Wanchai or Central I don't remember, to ask them about this company and have a good laugh.