I had an issue with my HSI, contacted Verizon and had the issue resolved relatively quickly.
see http://forums.verizon.com/t5/High-Speed-Internet-DSL-and-Dial/Intermittent-HSI-connection-Line-attenuation-Problem/td-p/595357
The repair man said my line was "pristine" so I expected no more problems.
I was a very happy camper until today (a day later) when my speed dropped again. This time to 1/3 the speed I had the day before.
I contacted verizon again via chat. They did some "tests". A few minutes they wanted to take over my computer to "check some settings". I said no, I can tell you what you need to know, Then they said they would send me a new modem. I said no I do not need a new modem. I have a new modem an it was working fine yesterday. I said just reset me to 3Mbps and turn off the bloody "OPTIMIZER" (see my post link above). They then "escalated" the issue to the network team. The chat session timed out.... I got a call moments later saying they turned the issue over to the network team and the issue would be resolved within 24 hrs. It was 10 minutes later that my speed was back to nearly what it was before.
My gut tells me they are deliberately throttling bandwidth. Most users would not notice, sending email and looking at facebook.
I am considering contacting a consumer advocate to investigate. Are others finding the same, their speed slowing down and told that it has been optimized for what the line can handle when they know they had better speed previously?