dude, i had almost the same problem, CALL your ISP and make complaints about that, make sure of having details abut your contract, type of connection, and whatever they could ask for, and then haer waht they got to say.
I had the same problem (slow download speed), and i made complaints, so they dindn't give me the pass for portforwarding, but remotly, they they activated something like DMZ, or anything like it, they sayd, with that activated, the router's firewall will be de-activated, and al traffic will port-forwarded to my pc's static IP....
Maybe asking them for that will solve the problem, and you to de-activate the protection on those ports.
BTW: my ISP makes P2P traffic shapping, but only for giving users time for considering waht they download