If I understand correctly PN would be using the RADIUS system to collect accounting information as a means to estimate the data usage etc.
I have recently had call logs sent to me which included Graphics from the RADIUS system detailing my connection times & durations.
The information in the call logs was completely wrong, stating periods of time when I was supposed to
not be logged in.
It displayed labels stating 'No connection for 17 days' and similar when in fact I never disconnect at all unless I am rebooting the modem.
PN when asked about this stated the following: (Direct Quote from reply)
Please ignore our visual RADIUS as there are times when it reports inaccurately and we are merely adding it to show a snapshot of the last couple of days or so. Of course, pending it is displaying these correctly.
I think this may support your contention that the error is on PN's side.