Where to hire a 12-seater minibus

Hi Everyone

I am looking to hire a 12 seater minibus to take my visiting family on a tour around. Our starting point would be Düsseldorf and I have been struggling to find large business who offer such a vehicle as most will only have up to 9 seaters. Does anyone know where I can find one? At this point, any business in and around, Düsseldorf, Krefeld, Cologne/Bonn, Dortmundw will be great.

Thank you

Watch out, mila, you need a special drivers license for any vehicle with more than 8 seats, driver's seat excluded. That's why the largest van you could find was a 9-seater.
EU-Führerschein D (German link)