I understand that the resyncs are a result of system maintenance within PN, whatever the cause. What I'm trying to understand is, these resyncs increased latency, can anything be done to reduce the increases?
If nothing in terms of interleaving and G.INP has changed at your end, then ball is in the Plusnet camp to do things like run gateways at a lower load or rebuild network to offer lower latency across more segments of it. Did you see your connection changing to a different gateway, and were these actual resyncs of the DSL or just the PPPoE or IP layer dropping for a short time.
There is almost always a way to reduce latency in a network, but the question is what cost and time will it take.