Although a smaller service, we were in a similar situation a couple of years ago. We assumed it was a competitor because there were not monetary requests, just a massive DDoS via torrents that lasted almost a week. Data center didn't help us in any way... it was crazy. Worst thing is that 90% of customers have no clue what a DDoS is and how hard it is to handle.
How is torrents protocol used to DDoS you? I never came across torrents being used as a DDoS. I would appreciate more details on what sort of torrent attack it was, and whether you found any ways of partially neglecting damage.
The attack is pretty clever, being indirect it is hard to trace and because bittorrent allows arbitrary ports you can hit a specific ip & port pair.
The one downside is the victims can be sure it is a bittorrent DDOS by checking the attacking connection's requests. The attacker's packets will contain bittorrent's magic connection bits.