Why is my downloading so slow?

Why is my internet downloading so slow all of a sudden?

• Last night my internet was fine and pumping out it's proper download speed of 12 mbps while trying to download ISO's. Today though it's downloading at about 1mbps and will shoot up to 3-4 mbps and than drop back down. I'm using the same website, even downloading the same ISO to make sure it's not a bad download link. I ran CCleaner, defragged, and ran a speedtest and it says it's pushing 12mbps but the file I'm downloading says otherwise. It's pretty ridiculous that were paying for this service that works half the time and the other half is slower than sh*t. Internet browsing is fine, it's incredibly fast but the downloading speed is retarded. There's no other programs running, no other wi-fi connections eating my bandwidth, there's really no reason I can think of for it to be running this slow other than my ISP trying to rip us off. It is sunday so MAYBE they're a little backed up but that's still no excuse for the performance to be 1/10 of what I'm paying for. Is there anything I can do to speed up my connection that I haven't already? any programs that will boost performance?

• Answer:

  This is very very normal. You simply have bad connection or someone else is connected to your network and taking up bandwidth. If you're using Mediacom, there's a saying for that, "Yay! My internet works... sometimes..." Mediacom slows down or shuts down their servers often. Which is why I don't like them. It should go back up within some time. If it isn't working withing a month, call a technician.