Your speeds still seem very low, so I still would keep contacting them. Ask them what download speed should you expect as a max.
Since your our speed with the Ethernet cable connected was the same as when on wireless, it's obviously not a wireless signal strength problem. Try booting in Safe mode with networking and see if that makes a difference. That eliminates some software issues.
you could also check with friends using Windstream and find out what their speeds are - tell them to measure using TestMy.net.
if you're using a laptop, you could take it to a friends house and run speed tests there and see if your results are any different.