Received a PCN (Penalty Charge Notice) EVERY time I have used them.
I first booked through them and parked at Sainsburys Nine Elms car park in the beginning of June and received a PCN which was within the time I have booked. They managed to appeal it for me and ensured the issue has been resolved. In beginning of July, I parked again and guess what, I have received another PCN by mistake.
To make it worse, before I have received my 2nd PCN, I have booked 3 times through them with a rental car in that space, which is the worse part! This is because car rental companies will pay the fine on your behalf and add administrative fee on top. And this is still dragging on at this moment as it involves YourParkingSpace, Enterprise Rent-a-car and Euro Car Park who monitors the premises.
So avoid YourParkingSpace, if not, please please please avoid Sainsburys Nine Elms if you want to find somewhere to park in London.