I have been having a problem with my TOT service- it turns out that somehow (since I have a WiFi set-up and use different computers at the same time) two different IP addresses are registered on my line, causing a conflict and slowing the internet speed down to a crawl.
If by some coincidence you have the same problem, it can't be fixed at your house- your ISP has to clear your line from their end (which is no big deal)- it took forever to figure this out (until I finally spoke to a tech that had a brain), but now that I know the cause, if it happens again I can at least tell the clueless tech what to do when I call the helpline.