All depends on the ISP, the only thing they guarantee is the speed and not the ping though isn't it?
So they'll probably just check the connection and say everythings fine.
Doesn't mean you shouldn't complain, but it'll probably be a headache (when isn't it) explaining it to them.
One thing you haven't said, is your internet working fine? Slow? Or do some images/parts of pages not load up.