Stop trying to communicate with a useless debt recovery agent. Powerless debt collectors rely on the low-hanging fruit on the gullible tree to pay up out of ignorance and fear.
Never ever communicate with a debt collector. Ignore them.
My advice is not to send a SAR. However, because you never updated your V5C when you moved, the unregulated private parking company, was given your old address by the DVLA. Updating your drivers licence does not update your V5C address. Do that now, online.
However, as this company cannot go back to the DVLA for another Keepers data request, they now hold an incorrect address for you. You must send the DPO of the parking company (not the useless debt recovery firm) a Data Rectification Notice (DRN) and instruct them to update their records with your current address for service and erase your old address. The highlighted words are there for a reason, so use them.
Also, stop giving these ex-clamper scummy firms a status they do not and could never have, of some kind of authority by calling these charges “fines”. By doing so, you are informing them that you have no clue about this and are “ripe for the picking”. A private company cannot issue a “fine”, only a speculative invoice for an alleged breach of contract by the driver.
Ignore any debt recovery letters, send the DRN and come back if/when you receive a Letter of Claim (LoC).