When you've had:
three new routers / modems (whatever they're called);
two providers
the line itself repaired with a (jelly-filled joint?)
and the speed still gradually diminishes to c. 1 mbps, at which point BT Sport ceased to work at all.
Openreach then relented, conceded that it might be the wire, replaced the wire from the telephone pole to the master socket, and the speed went up to +35 mbps, and was still at that (wifi, on my mobile) last time i checked (weekend).
During the replacement, the Openreach guy also managed to knock out the service to the next three houses, which took three days to rectify
