During the three months when my 80-20 VDSL was regularly reduced during the working day and evening to this typical example;
http://www.thinkbroadband.com/speedtest/results.html...
Whilst when the peak was over it always provided full speed overnight;
http://www.thinkbroadband.com/speedtest/results.html...
Zen refused my request to leave without paying an exit fee.
Eventually Zen upgraded their London Hub and my single thread degradation during busy periods disappeared.
Alas I notice that this type of peak time performance degradation is slowly returning;
http://www.thinkbroadband.com/speedtest/results.html...
But, I am now relieved to say that my initial 12 month VDSL contract period will end tomorrow.
Godfrey.