Dutch language for work

Hello!
I need to improve my Dutch in 6 months for my new job. I have finished first 4 levels at CVO (out of 7 levels), so I understand what people say if spoken clearly and slowly and I can speak ok, but I still cannot write much, especially for the business setting. Does anyone know if there is any school which offers a "Business Dutch for foreigners" kind of class, with focus on how to write business letter, how to speak, etc.??

I would prefer to go to class in Zavetem, north BXL, Vilvoorde, Mechelen area, but am willing to travel for a good school.

Thanks in advance for your help!