I dont know if they are throttling per se, but not giving a decent upload speed does that automatically. I also know that they know how to recognize certain packet types and on occasion do slow those packets to perserve quality of service for other consumers. But i do think its not fair to sell 12 meg service if they arent prepared to back it up. Just my opinion.
"And they'll say" we only list it as "up to" speeds.
I got so pissed at my cable service for the same reason. "Sure I have 3 Mb/s" but only at 2 AM!
At this time, they had way over sold the service and there were over 500 modems/customers on one node.
A year or two after I dumped them, they finally ran some more fiber and split the node.