Your frustration is understandable, but going into a case with the primary objective of causing the other party 'pain' is generally unwise. Consider 2 scenarios...
Scenario 1You receive a parking charge notice as a result of a 'double dip'. Confident that the charge has been incorrectly issued, you respond to ECP by way of an appeal, briefly setting out your evidence and explaining that the charge is not owed. They either accept this and cancel, or reject. If they reject, you appeal to POPLA, setting out the same evidence and explaining that the charge is not owed. POPLA either accept this and cancel, or reject. If they reject, ECP may then proceed to court. At this point, you submit a defence and Witness Statement, setting out your evidence, and also drawing attention to the repeated attempts you have made to resolve the matter, and drawing attention to ECP ignoring your compelling evidence and ploughing on with a hopeless case.
Scenario 2You receive a parking charge notice as a result of a 'double dip'. Wanting to inflict pain on ECP, you do not engage with the matter, with the hope that they will take you to court. When they eventually do, you suddenly produce evidence you have previously not shared, showing that you do not owe the money. Up until this point, ECP are unaware of the technical error that has occurred.
Which of the 2 scenarios do you think would yield the best chance of you convincing a court to award you costs on the basis that ECP have behaved unreasonably?
If you appeal, and show them clear evidence that you don't owe the money, and they
still take you to court, you'd have a fair argument that they have behaved unreasonably and should pay costs. If you don't engage, ECP could argue that a not insignificant part of the reason it has ended up in court is because you took no steps to resolve the matter prior to it going to court.
And when you say the court would take a dim view, how can this affect the driver?
If a judge takes the view that a party to litigation has behaved unreasonably, he can award costs to be paid by the party that has behaved unreasonably. In theory, a party can 'win' their case and still be deemed to have behaved unreasonably. It's quite a high bar, but why take the risk?
You could also look into misuse of personal data and making a claim for this, although this would be somewhat out of the remit of this forum. Again here though, in my view any such claim would be made stronger by showing that you had taken steps to inform them that they should not have accessed and now be continuing to process your data.