Hi Tony,
Could you give us a breakdown of the parts costs if you have them?
I'm just interested to know how much the discs cost to buy each.
If they've genuinely only covered 10k miles and are plenty thick enough (I would expect them to be - there should be a new and also a service limit thickness spec from MB), perhaps they could be very lightly skimmed by a reputable engineering firm.
It's very very unusual to get warped discs - and I wouldn't have thought that the pitting would be the cause of the vibration. Perhaps they have a buildup of pad material transferred onto the disc itself? This can easily cause the disc to feel 'warped' and show up as run out, which could give you the vibration under braking that you may have noticed.
FWIW, as far as a claim against MB goes, I think you're probably headed towards a dead end.
Will