The inspector wouldn't have deliberately put the wrong date, it happens, i've issued PF's with the wrong date, usually in the first few days of the month, like i said, the notice should not be issued with any mistakes on it and thus your appeal will be successful if you point out the error.
This is what they tell you. I was told it when I was first trained on Penalty Fares and also when I had RPI training recently. Staff actually genuinely believe it too, which is why that line about appealing and it will be successful all too often comes out.
I'd have believed it too, if it wasn't for my repeated experiences as a passenger. I've been on the other side, as a passenger more times than I care to remember.
The truth is, the people that deal with the appeals will do whatever they can to get out of approving the appeals - they run with the pretence that mistakes, inaccuracies and omissions on the paperwork are irrelevant and will reject the appeal, justifying it by turning the situation around on the customer. I've found this to be the case with both IRCAS and the RPSS, who will both err on the side of their customer, the TOCs if there is a discrepancy. I recently had IPFAS try to extract information from me in a roundabout manner to compensate for the RPI's failure to fill in the notice correctly - rather than approve the appeal on the basis the notice was not completed.
The appeals system is a sham. The sooner this is exposed and put right, the better all round I say.