Just FYI Germany likes to make things more difficult, so with federation every sub-area is separated in many aspects and has own agencies for different things…

BfDI is only responsible for health and internet-provider institutions (and a few more).
Otherwise you can send it to the one where the company is located at, or always where you are located at. (they will forward it, but that can take a few months, so better to submit where it has to go).