To get that much of a drop in speed, you either have a bad cable (oddly enough, DSL still works even if one wire is broken) or a ton more people in your neighborhood have signed up and the crosstalk in the cable has shot way up. If you haven't already done so, try to eliminate inside wire as a source of the problem. On my side of the pond, our demarc is a box on the side of the house and the newer protectors (in said box) have an RJ11 jack that you can just plug into and it disconnects the inside wire automatically. Older protectors need the inside wire removed manually and a test cable put in its place. If you can find said box (if applicable) also poke around and see how many pairs are in the cable coming from the field side, as sometimes a pair in the drop cable can go bad and you can try a spare pair if you have one (a technician from BT would need to swap them). Edit: Also, if you can log into your modem and post your current link stats, that would be useful.