Thank you for posting the PCN. The good news is that both you and your Mother are off the hook. The PCN does not comply with the Protection of Freedoms act 2012 so the charge CANNOT be transferred from the driver to the keeper. Only the driver is now responsible for the charge and as several thousand people with valid motor insurance policies are allowed to drive that car, good luck knowing who to pursue.
In order to be able to transfer the debt from the driver to the keeper PE must observe the wording of the Act. And they haven't. Schedule 4 S9 [2][e] states "
(e)state that the creditor does not know both the name of the driver and a current address for service for the driver and invite the keeper—
(i)to pay the unpaid parking charges; or
(ii)if the keeper was not the driver of the vehicle, to notify the creditor of the name of the driver and a current address for service for the driver and to pass the notice on to the driver;
If you read the PCN to your Mother it does not invite her to pay the charge nor to pass the PCN on to the driver. It may not sound much but it is a major mistake on PE's part and as such the liability to pay the charge is restricted to the driver only. If you have not appealed the PCN then you cannot as yet claim they have breached your Mother's GDPR in relation to sending numerous notices to her asking to pay when they were not aware that she was not the driver. Once she tells them that in her Witness statement and they continue to take her to Court, that is when her GDPR is breached since they should have dropped the case at the WS stage.
They have also not complied with the Act again since they are supposed to specify the parking.period. They have not. They have listed the arrival and departure times which is not the same since driving to the parking place from the entrance and driving from the parking space to the exit cannot be described as parking.
Whether you can argue that you were not parked even though you were there for almost two hours is a moot point.
i