English Language Courses (high proficiency) (Vienna)

Can someone recommend good English language courses in Vienna for someone who's already quite proficient but still wants to polish his/her language skills? Would Cambridge English / Business Certificates or Cambridge English CPE exam preparation courses be suitable or do those courses focus too much on the tests?

My English is pretty good, but since I'm using it now on a daily basis for business, I want to polish it, improve expressions and try get rid of my common mistakes:-)