Your ISP is responsible for dealing with this. They are the ones that negotiated the route you are using that is sending you through Cogentco to get to Ormuco (SE's ISP). Need to be in touch with your ISP's tier3 people. Let them know you have traces and such indicating potential packet loss or heavy shaping in route at their routing partner's hops that is negatively impacting your connection to the game servers. They should have an email that you can forward your data to--it may even be readily available via their website/forums.

You may also want to run some tests against a couple other popular services as well (like google/youtube, yahoo, netflix, justin.tv) to see if you can spot a similar pattern elsewhere. If you do, it can go a long way to encouraging them to investigate further.