agent,
Here in Europe I have several dormant accounts, both banks and brokers, I didn't count, but it could be 10 or so. Never have I been charged a single penny or was I asked to decide whether I wanted to use the account or else close it. In fact you get the impression they're happy to wait for you to come back some day.
So a dormant account costing them money, I don't believe that. And the only reason Datek comes up with themselves is their Streamer which I didn't have access to anyway.
aldrums,
I wouldn't be too sure. According to their own rules they will take from your account whatever they can get their hands on. So you may just have been lucky somehow. I read about someone else on this board having a zero account at Datek and still being able to use the Streamer. Maybe they just don't check very accurately.