First off, these are not fines. Only a court can impose a fine, not a transport body and certainly not a Private Parking Company (PPC).
Centro are using a Private Parking Company (VCS - Vehicle Control Services Ltd) to enforce the car park 'regulations' and VCS are members of the Accredited Trade Association (ATA) the Independent Parking Committee (IPC), not the British Parking Association (BPA).
Therefore, second stage appeals are dealt with by IPCs Independent Appeals Service (IAS), rather than the BPAs Parking on Private Appeals (POPLA).
https://www.centro.org.uk/transport/park-and-ride/considerate-parking-scheme/This is where it gets interesting though. Many, if not all of these Centro car parks will be on Railway or Midland Metro land and therefore subject to statutory control in the form of byelaws. Where land is subject to byelaws the Protection of Freedoms Act 2012 (PoFA) does not apply. It is PoFA that covers the rights of PPCs to pursue Registered Keepers (RK) of vehicles for Parking Charge Notices (PCN) issued on private land. And it is PoFA that requires an independent ATA to which second stage appeals can be made. If PoFA doesn't apply, as the land is subject to byelaws, then the PPC has no right to pursue the RK, and has no reasonable cause to request RK details from the
DVLA▸ . That's not to say that the DVLA won't release those details though as they get a fee for every request made.
Next is the issue as to whether Centro can even, legally, enforce the PCNs at the railway car parks. It is they who have engaged VCS as agents to manage the car parks. But Cento are likely only agents themselves. The landowners will be Network Rail, and the stations will be managed by a Train Operating Company. Therefore VCS are merely agents of an agent of a manager of a landowner. A very tenuous position to be able to legally enforce Parking Charge Notices in free car parks.
If the land is subject to byelaws and Centro are (through their agent VCS) going to issue PCNs backed up with the threat of criminal sanction through byelaws rather than PoFA, then this is also very dodgy legal grounds. Essentially they would be demanding a bribe to prevent a trip to the magistrates court. "Pay us ^100 or we'll take you to court". That could be deemed illegal.
A very convoluted state of affairs and I expect some interesting time ahead.