Welcome to the community and thanks for posting. Sorry to hear of your experience. Hopefully we can resolve this for you here. Quick question, where are you running the speed tests at? Your previous case notes also show that you've inquired about unidentified data usage as well. Seems you are familiar with the modem disconnect test. However to correctly see what is going on at your site, we are going to need screenshots. Take a look at this and follow all directions:
Please make sure to crop out your SAN. I'll be adding some token bandwidth to your account, so that you have plenty to work with while troubleshooting with us. As for speed tests. If you haven't already been running them on www.testmy.net, please head there to do them. We'll need tests throughout the day. Manual download tests of 12 MB size and manual upload tests of 2 MB size. Please post all your results here. Hope to hear from you soon.