Manhole cover missing or damaged

There is a defect on the road because I drove over it on the 28th April approximately around 03:40am. I heard a loud metal clanking noise but luckily my tyre did not get punctured. However I checked my car later on the day and there is damage to my bumper at the bottom and underneath the vehicle. Some parts of my bumper is missing because the damage was so deep. I have attached photos. I have no idea how long it has been there. But the defect is on that part of a406 it’s on the fast lane on the right side I think just before the 50mph average camera after the Bp Petrol station which is on the opposite side eastbound.