Demand escalation to someone who can. They have agreements with the big 3 top level ISP's...if nothing else they can get you to run through an alternate partner to see if things improve. TWC does it for me on a regular basis... but I've been dealing only with Tier3 technicians, not the people that answer the phone at the help desk. It also can't be done by the guys who come test your local setup either--this is something at a higher networking tier.
Just to test the idea out, you can sign up with a VPN service only for their free trial period... if things improve, it's a pretty solid sign that they need to address a routing issue between you and SE.
If after all that, they still refuse to budge.. you can contact the local regulatory authority. Details should be provided with your bill. They sometimes print it on the back of the stub you send in for payment... but it is supposed to be provided with your billing statement.
