I was on the train right behind the OP when this happened. The Revenue Protection Manager boarded at Milton Keynes so the next stop was Euston. She claimed that she needed to issue a PF because tickets are automatically refunded if uncollected, and thus some people avoid their fare that way.
I have no doubt that this might have been a method used by some people in the past, but since the refund changes on 1 April it is of course no longer possible. When I spoke to her after she had finished going through the train to correct her on this, she and her colleague insisted it was accurate and even claimed that she had checked with a manager and this was still the case. She knew about the refund rule changes but claimed they had only applied to eTickets and the position for ToD bookings was unchanged.
I have no idea where anyone gets such bunkum information - it certainly wasn't what the industry-wide briefing said. Indeed, excluding ToD would have been a pragmatic way of applying this change but the industry shied away from that - perhaps in fear of encouraging ToD uptake.
It's concerning that at least three members of WMT revenue protection staff are of this mistaken belief especially as it's certainly not the first instance of unprofessional behaviour we have heard of by WMT revenue staff. When I raised the ORR revenue protection review, whose recommendations included not penalising people where there is no possibility of revenue loss, the RPM unsurprisingly got rather defensive.
Fortunately for the OP (in a sense), she issued the PF incorrectly by charging the Off-Peak fare rather than the Super Off-Peak fare, thus giving the OP simple grounds for appeal. Of course that doesn't guarantee success at the first or second stage of appeal, but there is a good chance that an appeal will succeed at one of the three stages.
If the OP would like to post a draft appeal I'm sure we can provide feedback on it before they send it in. I'm sure we could also assist them in raising a separate complaint to WMT about the RPM's behaviour, though if previous experience is anything to go by, I wouldn't expect this to go anywhere.