Apparently, there are ways for very large network routers to intentionally re-route Internet traffic through particular pathways -- see, for example, the story at http://www.omninerd.com/articles/Did_China_Hijack_15_of_the_Internet_Routers_BGP_and_Ignorance. But I've never heard of any means for an individual "home user" to do such things, say, by programming their router to send traffic through a specific external pathway in order to avoid a particular, congested, intermediate IP address. I suppose you could ask your ISP, and show them the evidence you have for faulty transfer, Perhaps THEY can do something about their routing tables, but if the congestion is several hops downstream, they may not be able to do anything about it either.
You could try connecting through a proxy server.
Some people find that by connecting to a reputable proxy server this improves the routing. In fact, I have experienced this myself and gained some speed and stability on my stream.
You'd probably have to pay a small subscription each month though, to get a decent one.