Macbook Air Slow Download

I have seem to run across this a lot sense I transitioned to Mac. Currently I'm trying to download the newest OS "El Capitan" and it has been trying to download for 2 days and says it has 2+ days to complete the download. I just ran a speed test on my mac and connection and it came back with 56.83Mbps download and 12.76Mbps Upload. I don't think it should take me 4 day to download a 6GB file??? I can download an entire HD movie in less then 20 min on my PC form the apple store. Any ideas of what might be the issue??