Found this:
Audiotechnik Dietz Vertriebs GmbH, Benzstraße 12, 67269 Grünstadt, Tel:06359-93310

The country code for Germany is 49, so, from the states you'd dial
001-49-6359-93310
Most Germans speak enough English that I bet you could get by- at least get passed from a receptionist to an applications person.

Or try a simple email to [email protected]

Hope that helps-