I've been a customer for two years and had 40-60 Mbps down and 7-10 Mbps up. In the last week or so, the speeds are consistently down to 13 Mbps up and 0.6 Mbps down.
Unfortunately, I can't get my TAP 3 test results because BT's site errors out:
Same results with my Asus N66U router, BT HomeHub 3.
I have tried replacing ethernet cables too.
It was a fault with the line to the house. Promptly fixed!