read your agreement, It's "up to 40mbps". They are giving you exactly what you paid for. Don't like it, get enterprise grade with an SLA and then you can bitch when it's to slow...
I agree with you however on the overselling and monthly data limits, and the data rates should be best effort, or they should be sold as "XXmbps minimum, faster speeds may be available at some times" Then when there is congestion (say 6:30PM), they randomly select and throttle some people. TBH, if i could trust my ISP to handle throttling of my bittorrents, I would. Say "opt in for bulk download management" and then they can sort out long slow running things, and let the RTTs go up for those, or throttle those first.