Had various problems...
Firsty a provisioning problem from ISP to BT, that caused a setup delay.
Then a BT backhaul problem that cut me off for a weekend.
Then a failed VDSL port in the street cabinet.
Then a subsequent 11meg connection for 5 weeks. I got told to leave the system alone while it was learning - i.e. no modem reboots etc.
A loss of patience, followed by a power cycle of the Huawei BT modem got it back to 17 megs.
Replacing with the Thomson got me almost 20 megs and the line stats you see now.
Previous to that I've had:
An open circuit on one of the wires in the pair to my house.
The exchange has had a roof leak which rained on the racks in the exchange. Once my line fuse had turned green and gone open circuit, BT replaced it.
We've even had the pikeys steal 2km of trunk cable from the exchange to the street cab using a pickup and a tow ball.
We've had it all round here
Steve