@Walldawg, how are you getting on? Does the text of the regulations make sense? If you want evidence that those are the right regulations, you can see that Penalty Services link to them:
https://www.penaltyservices.co.uk/documents/. If you say what you're sure of and what you're not, people on here may be able to help.
I've called Transport Focus, partly to see if they might confirm the position to you about the regulations. They wouldn't normally get involved in a prosecution or an initial complaint, but I said this seems to raise an issue about the company's behaviour. They said you can send the correspondence to
[email protected] and they will see if they can help. If you want to phone first:
https://www.transportfocus.org.uk/contact/ . I'm not saying they will help, but it may be worth a go in case they can confirm that the regulations apply or are useful in any other way.
While theoretically Southeastern could have told the appeal panel in time that the penalty fare was cancelled, that seems unlikely: it would mean Penalty Services wrongly issued a decision. Also, Southeastern said in the "Statement of Facts" that the penalty fare remains unpaid. And it doesn't seem likely that they sent all the reminders before the decision of 8 March. You can say to Southeastern something like that they are barred from prosecuting, "unless you informed the appeal panel that the penalty fare was cancelled, before the appeal decision of 8 March".
If someone gets an SJP notice and chooses a court hearing rather than the single-justice route, the court then issues a summons to a hearing. Although the Magistrates' Courts Act 1980 says magistrates "must" do this, and must where the SJP requirements weren't met, higher courts have said that issuing a summons is a "judicial act" which shouldn't happen if there are compelling reasons not to. And if the magistrate understands that the prosecution is barred, issuing a summons would clearly be a waste of time. So hopefully even if SE refuse to accept the position, the "case" would end much earlier than a court hearing.