This must have been annoying & very distressing for the lady concerned.
When I owned a flat within a complex in the centre of Northampton, I saw the problem from the other side. Each of the forty-eight flats had its own numbered parking bay & the complex was monitored by private wardens. It was illegal for any of us owners to park in a bay which was not our own & we could be clamped for doing so. Many, many times I returned home to find a strange car parked in my bay, either clamped or not. I could not park anywhere else & had to park in the street after buying a ticket from a machine. Once, someone dumped an untaxed car in my bay. The police initially told me that they could do nothing because it was on private property. After three days, they relented and traced the owner. That evening the car had been removed.
The complex of flats was close to the main Northampton shopping centre and also to a church. The main offenders were shoppers, especially at Christmas, and also people attending weddings or funerals at the church. Yet there was a Pay & Display Car Park close by.
This is not a criticism, just an observation.