They are all very professional. I have trained business English there before, and I feel quite good.
They mainly study oral English with foreign teachers one-on-one through telephone and internet, using their own developed system, so you don't have to stay for training on Saturday and Sunday, and you can attend their classes every day as long as you are free.
Send you a link, you go and have a look They recently had a free course experience, and they will make a comprehensive evaluation of your English ability. You can try it first.