agency is not producing the proof

Loek van Kooten wrote:

Hi Brandis,

I sometimes use the services of a debt collection agency in Rotterdam which is operating worldwide, but to be honest it mostly doesn't come to this: just threatening is mostly more than enough.

That said, there's not much you can do with an agency in Rotterdam, as you live in Germany. I'd look on the internet for debt collection agencies in your area and compare their charging methods and fees.

Good luck!