Classic example of how not to go about dealing with a Parking Charge Notice (PCN). Forget about "considering" a counter claim". It is clear that you do not fully understand the process.
You are where you are and we will assist in dealing with what would have been a simple matter to deal with and get cancelled.
Never, ever, EVER, EVER identify the driver! Until you blabbed the drivers identity, the parking operator had no idea who that was. In most cases, the Notice to Driver (NtD) that was on the windscreen is not PoFA 2012 compliant, which means that they cannot transfer liability from the unknown driver to the known Keeper. If they don't know the identity of the driver, there is nothing that can do about it.
The next thing the Keeper should have done is not appealed until day 27 after the NtD was issued. Only then, should the Keeper have appealed, without identifying the driver.
FOr now, you can safely ignore all debt recovery letters. Debt collectors are powerless to do anything except to try and persuade the low hanging fruit on the gullible tree to pay up out of ignorance and fear.
Come back when you receive. Letter of Claim (LoC),