Block paving road subsidence at entrance to Penlon Place

Penlon Place (an estate with 200+ flats) has a block paved road/carriageway. At the entrance there is a circular patch approx 1metre in diameter where the blocks are subsiding, causing them to be uneven and sticking up from the flush surface. On inspection tonight one of the blocks was approximately 3" raised from the surface. The area is the sole area in and out of the estate and therefore heavily trafficked. It has been noticeable for a number of months, but significantly deteriorated in the last 2weeks or so. It now collects a pool of water from the rain and more and more of the blocks are loosened, cracked and starting to degrade.