Look at the dates they're charging you for. It it lines up to when you actually cancelled your plan then this is actually your final bill. If the dates don't make sense, call em and ask what's the final balance on your account?
You're paying for: UP TO 50mbps, not 50mbps exactly. Your speed is dependent on the wiring in your area. You can't control it. You can try using cable internet for your area and see if that's better.
