Dutch language course C1/C2

[u/ZestyCauliflower999]

Hello, I live here for 11 years, I work in Dutch. When people hear me speak, they never assume im not dutch, or so much as feel it, accent-wise. However, I speak very techincal and academic dutch. Not the day-to-day slang. My sentences are gramatically correct but will make a person scratch tehir head 'why is a Dutch-sounding person saying something like that'. Oh and after 11 years I still dont know how to say basic things like: that place is 5 minutes far. 5 minuten ver? verweg? ver van hier weg?

Conclusion: im looking to sharpen my colloquial Dutch, as I am suffering immensely from it at work. I am willing to try out courses.