Dangerous road surface

I am a motorcyclist and frequently travel on the M3 westbound at the flyover at Sunbury roundabout. In the middle lane about half way across the flyover a large panel in the road surface has been replaced with seems to be a concrete slab about 6 feet long and 4 feet wide. It is like riding over a sharp dip or ramp and at the deepest point is probably 8inches below the road surface. It is on the brow of the flyover so is very difficult to see/anticipate and because of it is large size very difficult to avoid. There is no warning of this in the approach and the speed limit is not reduced. Riding over this "ramp" at any speed over 50mph on a motorcycle is incredible dangerous. My view is that may lead to a fatality and must be dealt with promptly. I have kept a record of this report and will be monitoring local news for accidents. It is shocking that a motorway has been left in such a dangerous condition. I note that this has been reported many times but no action has been taken to remedy this or reduce speeds.