There's a precedent for this date issue.
This happened in Edinburgh a few years ago though they managed to avoid refunding much of the 'revenue'.
Though the date issue was undeniable, they clung to a legal opinion that payment of the fine, rather than challenging it via the established procedure, was an admission of guilt.
I expect that the same argument will be relevant in this case though, as the article says, any additional fines or recovery fees charged as a result of the original offence may be refundable.
It's all a bit murky and underhand, hence the pickpocket...
It doesn't seem right to be able to retain the money when the correct process, I believe it's called The Law, wasn't followed and it's only the rule of law that allows the fine to be levied.