Park Up Meet & Greet is a 'booking agent' for Blue Circle Parking, and if you check online they have terrible reviews. Notice that Park Up Meet and Greet are very careful not to mention anywhere that it will be Blue Circle fulfilling the booking.

I used them at Heathrow T3 recently, and when I collected my car discovered coins had been stolen from a closed compartment in the centre console. I had taken a photograph of the coins when I dropped off the car so I know exactly how much was taken. We'll see what Park Up Meet & Greet and Blue Circle do to resolve this. It's a small amount of money taken, but it's the principle, plus lots of small amounts will soon add up.