Why did you do that? -->

"As soon as transaction ID 21509 was canceled I have a angry letter that I'm joking whit her and I have to send 25 BTC to
bitcoin adress: 19TAxzRfA8SPGn6Vi6oVrSmBRnCi4q8NW2. Ofcourse I do this right away." WTF?! Why?

This part is your own fault and I see no way for Bitmarket to help you here. You do not send money (Bitcoins) that are irreversible to anyone without a guarantee to get your "product". If you had used bitmarket instead, it would have been safer. That's just my 2cents.

However the person was able to get back the money from your bank account is very strange to me as well, normally there is no way to get back your money from a regular bank transfer. The moment you send it you do it voluntarily, and it is gone for good. Not even the police could get it back for you directly from that bank account.

I strongly suggest that you file a police report as soon as you can and show the police your bank statements. You were robbed, not sure how the admin could help you here. I'm sure he has already banned named user from Bitmarket.