I think that recent comment about Plusnet's network being out of balance was referring to a couple of recent events which won't have helped matters, but can't be responsible for the ongoing issues.
The graphs have looked a total mess recently, but it was still possible to spot that all the users got dropped off pcl-bng01 on Wed 11 March, and on Fri 13 March it looks like there were very few users on pcl-ag02 (and there were some service status messages yesterday).
I have been on PCL bng01 since the 11th @10:30pm , The said gateway has endpoints for me that are better for latency than some of the others, both this gateway and PCL BNG 02 always seem to end up with more customers connected than the other bng's maybe lower latency is a factor for everyone ? but there are some endpoints to PCL BNG 01 that have really poor performance at peak times , i do seem to see low level packet loss more so on the ping monitor, in particular when streaming something on youtube
usage last night was lower than it was on the 12 and other nights this week , even so single stream throughput was still affected ,but not as severely as previous nights, there also was the absence of the useual peak time increase in latency ,though there was a small increase in the level of jitter, but overall a better night that the rest of this week,
Those plusnet graphs don't show the full picture IMO, so probably serve to confuse things further maybe ?