Thanks guys .......................
It is simply because all our local Garages haven't moved with the times, and aren't interested in doing much more than an Oil and Filter, MOT Tests and MOT Repairs, all this kind of stuff is beyond them, and they have had their fingers burnt before, so all they do is send their customers to me !!
This is why I am so busy these days
This is a common failure, rust or ham - fisted mechanic doing other jobs is the cause.
It is a metal toothed ring on the back of the Hub, and I think MB do it separately from the Hub, see pix below apologies for quality I robbed them lol.
Newer Cars are now using a Magnetic Seal in the Hub Bearings as the trigger, and these are rotting, delaminating and failing inside a few years
Rears can be a right arse to do as you need to remove the whole assembly to press in a new Bearing assembly
As your Indie is saying all Teeth are present tell him I said to look for play in the Wheel Bearing, a piece of rusty debris in between teeth, or run out on the Ring, (i.e. it is moving away from the Sensor as it rotates), it doesn't need much to get spurious wave pattern and then ESP / ABS Module throws a fit