I believe you need rotors. Turning these rotors is not a good thing, their border line thin to begin with. Turning them reduces the mass to a point where they can't hold as much heat. I believe that this led to the additional warping.
Check with the parts shop on this site. The rotors are not terribly expensive, nor very difficult to change.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in